"Exposing to the right" is over exposed, what now?

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

You overexpose short of clipping, the apply a likewise (if preferred) reverse adjustment in post. This is to maximize the signal-to-noise and tonal gradations in the exposure.

The tonal aspect is analogous to setting a digital multimeter to the proper scale before taking a reading, in order to maximize the significant digits.

In article ,
John A. wrote:

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

You overexpose short of clipping, the apply a likewise (if preferred) reverse adjustment in post. This is to maximize the signal-to-noise and tonal gradations in the exposure.

The tonal aspect is analogous to setting a digital multimeter to the proper scale before taking a reading, in order to maximize the significant digits.

This blog article talks about making the best of exposing to the right.

http://www.luminous-landscape.com/tutorials/right-hista.shtm l

Do you have more to say about which way you set exposure and when? I am genuinely interested in how you decide to set exposure. At this point I actually use both, "expose to the right" and light meter, for the "fine art" shots. I can’t see a difference, I was just curious in a CD versus vinyl sort of way.

Do you have more to say about which way you set exposure and when?

Porte Rouge wrote:

   Do you have more to say about which way you set exposure and when?

One more thing about histograms in the camera: at least in Canons, they are made from the in-camera jpeg!

useful, you have to set the camera to make jpegs using "faithful" mode,

You also need to use the "flashing overload" indicator on the camera review screen. If you set contrast to 0 or more (remember, this is Canon) and trust the histogram, you will still lose dynamic range.
Experience.

Doug McDonald

Doug McDonald wrote:

taylor aldler wrote:

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) …

… doesn’t seem to be obvious to you. Instead of learning how to expose each scene properly and not rely on dumbed-down point and shoot snapshooter’s suggestions (like "expose to the right", which only applies to very few subjects) or depending on your automatic point and shoot modes
of your camera, you’ll forever be wasting your time in editing instead of taking photos the right way to begin with.

This is what you get for taking to heart the lame "one size fits all" dumbed-down snapshooters suggestions made by all point ‘n shooters and armchair photographers on the net.

This sounds like the P&S troll.

"Exposing for jpeg" which is what he proposes is NOT the absolute best way to use a more capable camera like a dSLR.

That is, indeed, to expose for the highlights, putting them just under the clipping value, and save as raw. Fix later in the raw->jpeg conversion.

And by the way, allowing some highlights to clip (direct lighting, some specular reflections) is quite alright, otherwise you’ll push the middle down into the shadows and increase noise.

This is where good spot metering skills come in.

On Oct 4, 1:52 pm, Doug McDonald
wrote:

Porte Rouge wrote:

   Do you have more to say about which way you set exposure and when?

One more thing about histograms in the camera: at least in Canons, they are made from the in-camera jpeg!

Do you know if this is true of the Nikon D200?

This means that to make them

useful, you have to set the camera to make jpegs using "faithful" mode,

I’m sorry, what is "faithful" mode?

and contrast set to -3 or -4. Even so, it is only approximate.

You also need to use the "flashing overload" indicator on the camera review screen. If you set contrast to 0 or more (remember, this is Canon) and trust the histogram, you will still lose dynamic range.
Experience.

Doug McDonald

I use the flashing overload indicator, too. It sounds like I need to do some test shots and see if clipped in the camera LCD is clipped in ACR or Lightroom.

In article ,
John A.   wrote:

On Sun, 4 Oct 2009 06:25:12 -0700 (PDT), Porte Rouge
wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

You overexpose short of clipping, the apply a likewise (if preferred) reverse adjustment in post. This is to maximize the signal-to-noise and tonal gradations in the exposure.

The tonal aspect is analogous to setting a digital multimeter to the proper scale before taking a reading, in order to maximize the significant digits.

This blog article talks about making the best of exposing to the right.

http://www.luminous-landscape.com/tutorials/right-hista.shtm l —
Al Dykes
 News is something someone wants to suppress, everything else is advertising.     – Lord Northcliffe, publisher of the Daily Mail

On Oct 4, 11:39 am, Robert Spanjaard wrote:

On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:

… doesn’t seem to be obvious to you. Instead of learning how to expose each scene properly and not rely on dumbed-down point and shoot snapshooter’s suggestions (like "expose to the right", which only applies to very few subjects) or depending on your automatic point and shoot modes of your camera, you’ll forever be wasting your time in editing instead of taking photos the right way to begin with.

This is what you get for taking to heart the lame "one size fits all" dumbed-down snapshooters suggestions made by all point ‘n shooters and armchair photographers on the net.

This sounds like the P&S troll.

"Exposing for jpeg" which is what he proposes is NOT the absolute best way to use a more capable camera like a dSLR.

That is, indeed, to expose for the highlights, putting them just under the clipping value, and save as raw. Fix later in the raw->jpeg conversion.

Your method is not the absolute best way either. There is no absolute best way.

—
Regards, Robert                                    

Porte Rouge

Oct 5, 2009

On Oct 4, 11:06 pm, taylor aldler wrote:

On Sun, 4 Oct 2009 09:47:45 -0700 (PDT), Porte Rouge

wrote:

On Oct 4, 11:39 am, Robert Spanjaard wrote:

On Sun, 04 Oct 2009 10:17:25 -0500, Doug McDonald wrote:

… doesn’t seem to be obvious to you. Instead of learning how to expose each scene properly and not rely on dumbed-down point and shoot snapshooter’s suggestions (like "expose to the right", which only applies to very few subjects) or depending on your automatic point and shoot modes of your camera, you’ll forever be wasting your time in editing instead of taking photos the right way to begin with.

This is what you get for taking to heart the lame "one size fits all" dumbed-down snapshooters suggestions made by all point ‘n shooters and armchair photographers on the net.

This sounds like the P&S troll.

"Exposing for jpeg" which is what he proposes is NOT the absolute best way to use a more capable camera like a dSLR.

That is, indeed, to expose for the highlights, putting them just under the clipping value, and save as raw. Fix later in the raw->jpeg conversion.

Your method is not the absolute best way either. There is no absolute best way.

—
Regards, Robert                                    

Charles

Oct 5, 2009

Porte

For me, digital is the opposite of film in exposure emphasis. In film, you expose for the shadows, while in digital you should expose for the highlights.
You can’t print underexposed shadows on a film negative but you can burn in overexposed highlights since the negatives tend to hold some information in that area.
You can’t print overexposed highlights in a digital image but you can tease out information from underexposed shadows in digital processing. You can’t treat your entire image the same way, so you need to apply techniques similar to dodging and burning in the digital realm using area adjustments of an image and the various tools/techniques available in image editors.

Exactly! The clipping that occurs in digital photography is rather harsh …. all scene details more luminous than the clipping (saturation of the sensor) point are gone, gone, gone. You can’t tease them out with any amount of post-processing, regardless of how heroic or exotic. I fail to understand why such a basic concept is so hard to understand.

Film does not "clip" in the same manner and some folks just don’t seem to get it. There are curves with soft knees and then there are curves with very sharp knees. They are very different (in terms of useful output) when the input data approaches and exceeds them. A soft knee means that there is compression of the data and that means that a correction that employs decompression can restore the data, at least to some extent.

So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

Doug McDonald

Oct 5, 2009

Charles wrote:

So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

The point is to expose to the right if you can’t afford to lose low light detail, just be careful to avoid sensor overload where you don’t want it.

It works just fine, unless you are an idiot
P&S troll that just wants to depend on P&S to do his job.

Doug McDonald

floyd

Oct 5, 2009

"Charles" wrote:

Porte

For me, digital is the opposite of film in exposure emphasis. In film, you expose for the shadows, while in digital you should expose for the highlights.

Actually, since film is a negative, the two are in fact
actually the same. Expose for the brightest range of the *recording* *mechanism*.

That just happens to be the dark areas of a scene with
film (where the negative is clear) and the bright areas
of a scene with an electronic sensor (the highest
voltage output).

You can’t print underexposed shadows on a film negative but you can burn in overexposed highlights since the negatives tend to hold some information in that area.

You can’t print overexposed highlights in a digital image but you can tease out information from underexposed shadows in digital processing. You can’t treat your entire image the same way, so you need to apply techniques similar to dodging and burning in the digital realm using area adjustments of an image and the various tools/techniques available in image editors.

Exactly! The clipping that occurs in digital photography is rather harsh … all scene details more luminous than the clipping (saturation of the sensor) point are gone, gone, gone. You can’t tease them out with any amount of post-processing, regardless of how heroic or exotic. I fail to understand why such a basic concept is so hard to understand.

Digital clipping is almost never "saturation of the sensor". Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

Film does not "clip" in the same manner and some folks just don’t seem to get it. There are curves with soft knees and then there are curves with very sharp knees. They are very different (in terms of useful output) when the input data approaches and exceeds them. A soft knee means that there is compression of the data and that means that a correction that employs decompression can restore the data, at least to some extent.

That is easy enough to do with digital too, though
obviously "expose to the right" does not do it. And it should be noted that technically such a compression
curve adds a "noise" to the image! People get all excited about digital "noise", but rarely understand what it is, or that such things as the supposed
"latitude" of film constitutes a significant addition of noise to an image. (Technically it is a "distortion".)

So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

False.

If you apply the philosophy of "expose to the right" there will be no loss of highlights, unless of course
you *want* to blow some of them away. And that is
commonly the exact desire for such things a light
sources, reflections, etc.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Paul Furman

Oct 6, 2009

Porte Rouge wrote:

Al Dykes wrote:

John A. wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

You overexpose short of clipping, the apply a likewise (if preferred) reverse adjustment in post. This is to maximize the signal-to-noise and tonal gradations in the exposure.
The tonal aspect is analogous to setting a digital multimeter to the proper scale before taking a reading, in order to maximize the significant digits.

This blog article talks about making the best of exposing to the right.

http://www.luminous-landscape.com/tutorials/right-hista.shtm l

Wow, good stuff. I had to run out and get my camera and check the settings. I don’t understand what he says about the white balance. I have it set on auto and have ignored it when shooting RAW. Should I adjust it for each lighting condition when I shoot and this will give me a truer histogram?

WB can effect the histogram a lot if you make wild adjustments but auto is usually close enough to not matter much I’d guess.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

floyd

Oct 6, 2009

Paul Furman wrote:

Porte Rouge wrote:

Al Dykes wrote:

John A. wrote:

This blog article talks about making the best of exposing to the right.

http://www.luminous-landscape.com/tutorials/right-hista.shtm l

Wow, good stuff. I had to run out and get my camera
and check the
settings. I don’t understand what he says about the white balance. I have it set on auto and have ignored it when shooting RAW. Should I adjust it for each lighting condition when I shoot and this will give me a truer histogram?

WB can effect the histogram a lot if you make wild adjustments but auto is usually close enough to not matter much I’d guess.

Sort of depends on how close is "enough". But auto isn’t any different than a wild guess as far as the
histogram goes!

The basic problem is that the sensor has twice as many
green sensors as red or blue sensors, and thus a
"correct" histogram should take that into account, but doesn’t. If WB actually is adjusted to make the
histogram more correct, the JPEG image produced (and
displayed by the camera) will be quite greenish, and not exactly appealing. (Which means you don’t want to show
it to anyone, and have to wait until after the RAW data
is post processed to let anybody see it.)

What is gained, however, is probably not of great
advantage. All you really need to know is that the
right edge of the histogram (and the point at which a
highlight display starts to blink) is probably about 1/2 to 3/4 of an fstop below maximum exposure. Take your
pick… set exposure to where the brightest highlight
just barely blinks, and you lose just under 1 fstop of
dynamic range, but gain exactly that much "latitude" for over exposed highlights. Or set the exposure about 1/2
to 3/4 an fstop past where the brightest highlight
blinks to get maximum dynamic range (and no latitude).

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Doug McDonald

Oct 6, 2009

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping. At -4 the blinking clip display, the histogram, and the raw file all agree well about how close you are to clipping.

And yes, I do look at the in-camera histogram. It works.

Doug McDonald

floyd

Oct 6, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping.

The brightest part will still show at *exactly* the same place. If you set exposure so that the brightest part
of the histogram is just barely less than the right edge of the graph, it will be the same regardless of how
in-camera contrast is set. What contrast will change is how much of the area of the graph is spread out over the entire graph (low contrast) as opposed to being peaked
in some portion of the graph (high contrast).

Changing the contrast does *not* change the value of the brightest part of the image, which is what you use to set exposure by the "expose to the right" method.

At -4 the blinking clip display,
the histogram, and the raw file all agree well about how close you are to clipping.

If you want to see a good demonstration of how it works, set your camera to maximum contrast, use manual
exposure, and take a picture of an indoor light fixture. It will be dramatic if the area around the light fixture is relatively white and there is little light from any
source other than the fixture. Zoom in or be at a
distance where the light fixture is a significant part
of the image area, but most of it is the area around the light and thus darker.

Look at the histogram, and experiment with exposure.
The idea is to find the exact exposure where the
histogram bumps the right side of the chart. More
exposure will cause a spike to climb up the right side,
less exposure will cause gap to form between the graph
and the right side. Perhaps the ideal exposure for this experiment is where there is just a small spike, because it will be easiest to compare the height of the spike to see if exposure changes.

Once you have that, adjust the in-camera contrast
setting from maximum to minimum, and check the histogram for each exposure. What you’ll find is that the little
spike at the right side doesn’t change. What does
change is the spread of the less bright areas of the
image. If you shoot a bare bulb and have a dark
background the entire bulk of the graph will be over on
the left side. It will be wider with lower contrast and narrower for high contrast. The amount of area will
depend on how closely you zoom in on the light fixture
(the ratio of light source to background), and the
spread that it has along the right side of the histogram will depend on the difference in brightness of the light and the background.

Adjust the physical attributes to get a useful
histogram. Then change the contrast setting to see what it actually does affect.

And yes, I do look at the in-camera histogram. It works.

But what do you look for? Not the distribution of the
area under the graph! That’s what the contrast setting
will change. It does not change the highest value of
the displayed graph though (which exposure does change).

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Tech Play

Oct 6, 2009

On Mon, 05 Oct 2009 21:18:08 -0500, Doug McDonald
wrote:

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping. At -4 the blinking clip display, the histogram, and the raw file all agree well about how close you are to clipping.

And yes, I do look at the in-camera histogram. It works.
Doug McDonald

If you had a CHDK capable camera, you could use any of the various live-view RGB color histograms to find out which of any color channels need to have their contrast reduced too. I found that an overall -2 on contrast on the "custom color" settings along with a -2 setting on the R channel of Canon cameras gives a more accurate rendition, provides maximum dynamic range, and doesn’t clip the R channel first on highlights. I could reduce B and G by a -2 also for even more dynamic range, but then I’d lose out the nice balance. And, quite frankly, it already has more dynamic range than any film I used to use, so it’s not all that important. Few if any interesting and well composed shots will benefit from more dynamic range. A large dynamic range is the crutch of snapshooters that don’t know how to properly expose a subject in the first place and will then always try to depend on post-processing to fix all their beginner’s errors.

Eric Stevens

Oct 6, 2009

On Mon, 05 Oct 2009 17:58:51 -0800, (Floyd L.
Davidson) wrote:

Paul Furman wrote:

Porte Rouge wrote:

Al Dykes wrote:

John A. wrote:

This blog article talks about making the best of exposing to the right.

http://www.luminous-landscape.com/tutorials/right-hista.shtm l

Wow, good stuff. I had to run out and get my camera
and check the
settings. I don’t understand what he says about the white balance. I have it set on auto and have ignored it when shooting RAW. Should I adjust it for each lighting condition when I shoot and this will give me a truer histogram?

WB can effect the histogram a lot if you make wild adjustments but auto is usually close enough to not matter much I’d guess.

Sort of depends on how close is "enough". But auto isn’t any different than a wild guess as far as the
histogram goes!

The basic problem is that the sensor has twice as many
green sensors as red or blue sensors, and thus a
"correct" histogram should take that into account, but doesn’t. If WB actually is adjusted to make the
histogram more correct, the JPEG image produced (and
displayed by the camera) will be quite greenish, and not exactly appealing. (Which means you don’t want to show
it to anyone, and have to wait until after the RAW data
is post processed to let anybody see it.)

What is gained, however, is probably not of great
advantage. All you really need to know is that the
right edge of the histogram (and the point at which a
highlight display starts to blink) is probably about 1/2 to 3/4 of an fstop below maximum exposure. Take your
pick… set exposure to where the brightest highlight
just barely blinks, and you lose just under 1 fstop of
dynamic range, but gain exactly that much "latitude" for over exposed highlights. Or set the exposure about 1/2
to 3/4 an fstop past where the brightest highlight
blinks to get maximum dynamic range (and no latitude).

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?

I do, and I expect many others would also.

I take it from this question you do not do this and take your exposures as you find them.

It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

With respect, you are wrong. The in-camera histogram will help you adjust your exposure if the first one is not right.

Eric Stevens

DPeterMaus

Oct 6, 2009

On 10/5/09 16:44 , Charles wrote:

Porte

For me, digital is the opposite of film in exposure emphasis. In film, you expose for the shadows, while in digital you should expose for the highlights.
You can’t print underexposed shadows on a film negative but you can burn in overexposed highlights since the negatives tend to hold some information in that area.
You can’t print overexposed highlights in a digital image but you can tease out information from underexposed shadows in digital processing. You can’t treat your entire image the same way, so you need to apply techniques similar to dodging and burning in the digital realm using area adjustments of an image and the various tools/techniques available in image editors.

Exactly! The clipping that occurs in digital photography is rather harsh … all scene details more luminous than the clipping (saturation of the sensor) point are gone, gone, gone. You can’t tease them out with any amount of post-processing, regardless of how heroic or exotic. I fail to understand why such a basic concept is so hard to understand.

You’ve answered your own questions, here.

Film does not "clip" in the same manner and some folks just don’t seem to get it. There are curves with soft knees and then there are curves with very sharp knees. They are very different (in terms of useful output) when the input data approaches and exceeds them. A soft knee means that there is compression of the data and that means that a correction that employs decompression can restore the data, at least to some extent.
So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

Not all highlights contain details. These can be lost. That reflection in a Packard’s bumper on a bright, sunny day is just a bright spot. Expose to retain that detail and you’ll be looking at the kind of night shot done by Hollywood in the days of "Yancy Derringer."

Accept that those specular reflections contains no detail, and you can easily expose more ‘to the right’ without any loss of image detail, while recovering more low light detail with lower noise.

Dynamic range compression with film was a limitation that shooters learned to work around, embrace, or simply accept. And like tape hiss in analog audio, it covered a multitude of sins.

The linear nature of digital is no different. It’s a limitation that requires practical evasions. You either learn to work with it, or not. And the output reflects your choice.

floyd

Oct 6, 2009

Eric Stevens wrote:

On Mon, 05 Oct 2009 17:58:51 -0800, (Floyd L.
Davidson) wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?

I do, and I expect many others would also.

I take it from this question you do not do this and take your exposures as you find them.

As I noted, the *shape* of the curve has absolutely
nothing to do with setting exposure.

If you check the shape, what you learn is the tonal
distribution within the recorded dynamic range, not the
range itself. The histogram shape, and thus the
in-camera contrast setting, is useless and has no effect at all on the camera raw data that is later manipulated
with post processing.

It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

With respect, you are wrong. The in-camera histogram will help you adjust your exposure if the first one is not right.

You need to learn to read a little better Steven.

The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Paul Furman

Oct 6, 2009

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping.

The brightest part will still show at *exactly* the same place.

Maybe for contrast (though I doubt it) but WB makes a big difference. I just tested at 25K & 100K, the highlights are completely different. I’m looking at split RGB histograms btw.

If you set exposure so that the brightest part
of the histogram is just barely less than the right edge of the graph, it will be the same regardless of how
in-camera contrast is set. What contrast will change is how much of the area of the graph is spread out over the entire graph (low contrast) as opposed to being peaked
in some portion of the graph (high contrast).

Changing the contrast does *not* change the value of the brightest part of the image, which is what you use to set exposure by the "expose to the right" method.

At -4 the blinking clip display,
the histogram, and the raw file all agree well about how close you are to clipping.

If you want to see a good demonstration of how it works, set your camera to maximum contrast, use manual
exposure, and take a picture of an indoor light fixture. It will be dramatic if the area around the light fixture is relatively white and there is little light from any
source other than the fixture. Zoom in or be at a
distance where the light fixture is a significant part
of the image area, but most of it is the area around the light and thus darker.

Look at the histogram, and experiment with exposure.
The idea is to find the exact exposure where the
histogram bumps the right side of the chart. More
exposure will cause a spike to climb up the right side,
less exposure will cause gap to form between the graph
and the right side. Perhaps the ideal exposure for this experiment is where there is just a small spike, because it will be easiest to compare the height of the spike to see if exposure changes.

Once you have that, adjust the in-camera contrast
setting from maximum to minimum, and check the histogram for each exposure. What you’ll find is that the little
spike at the right side doesn’t change. What does
change is the spread of the less bright areas of the
image. If you shoot a bare bulb and have a dark
background the entire bulk of the graph will be over on
the left side. It will be wider with lower contrast and narrower for high contrast. The amount of area will
depend on how closely you zoom in on the light fixture
(the ratio of light source to background), and the
spread that it has along the right side of the histogram will depend on the difference in brightness of the light and the background.

Adjust the physical attributes to get a useful
histogram. Then change the contrast setting to see what it actually does affect.

And yes, I do look at the in-camera histogram. It works.

But what do you look for? Not the distribution of the
area under the graph! That’s what the contrast setting
will change. It does not change the highest value of
the displayed graph though (which exposure does change).

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Doug McDonald

Oct 6, 2009

Floyd L. Davidson wrote:

As I noted, the *shape* of the curve has absolutely
nothing to do with setting exposure.

If you check the shape, what you learn is the tonal
distribution within the recorded dynamic range, not the
range itself.

For the Canon 30D, that is incorrect. True, you do learn the shape.

But at contrast levels (as described in the camera setup) of -3 or 0-, you **DO** learn at least the high end of the contrast range. Do you understand this? That is, at -3 or -4, there is enough detain in the in-camera histogram to tell, quite accurately, how close you are to overload of the raw file. At -2 or higher, the compression of the (internal) jpeg from which the histogram is made makes telling that problematic.

The histogram shape, and thus the
in-camera contrast setting, is useless and has no effect at all on the camera raw data that is later manipulated
with post processing.

At settings more than -3, that is true always, and yes,
it has no effect on the raw file.

It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

With respect, you are wrong. The in-camera histogram will help you adjust your exposure if the first one is not right.

You need to learn to read a little better Steven.

The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

THAT LAST PARAGRAPH IS INCORRECT FOR THE CANON 30D!

Changing the in-camera contrast setting DOES change how close the graph approaches the right side. REALLY!! I’ve tried it many times. Changing the in-camera contrast setting seems to expand or contract the histogram about some point in the middle. I’m not saying its the exact center, I have not tried telling. I could do this, but have not.

Have YOU examined the histogram on a Canon 30D?

If you have not, I suggest that you preface your remarks with "on the cameras I have actually personally tested i.e.
[list of cameras] …".

Doug McDonald

Eric Stevens

Oct 6, 2009

On Tue, 06 Oct 2009 00:52:09 -0800, (Floyd L.
Davidson) wrote:

Eric Stevens wrote:

On Mon, 05 Oct 2009 17:58:51 -0800, (Floyd L.
Davidson) wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?

I do, and I expect many others would also.

I take it from this question you do not do this and take your exposures as you find them.

As I noted, the *shape* of the curve has absolutely
nothing to do with setting exposure.

If you check the shape, what you learn is the tonal
distribution within the recorded dynamic range, not the
range itself. The histogram shape, and thus the
in-camera contrast setting, is useless and has no effect at all on the camera raw data that is later manipulated
with post processing.

It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

With respect, you are wrong. The in-camera histogram will help you adjust your exposure if the first one is not right.

You need to learn to read a little better Steven.

The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

But not in the RAW data, surely? Are you talking shooting JPEGs – or what kind of camera is it?

Eric Stevens

Charles

Oct 6, 2009

Digital clipping is almost never "saturation of the sensor". Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

And what difference would that make? There is no sharper knee than one imposed by basic mathematics. 2^8 = 256, is a simple example. With 8 bits, the maximum value is 255, base 10, with NO exceptions possible. You actually help to make the case that over-exposed digital shots guarantee lost information in the bright portions of the scene.

I continue to believe that exposing to the right is perpetuated by folks with limited experience and knowledge. They are perhaps into the dark parts of scenes and don’t understand dynamic range. Many of us are more greedy and want details at both ends of the luminosity range.

Hey, blow those high-lites out! If that is the intended message of a given scene, go for it. I don’t care for over-exposed shots … they are just not my thing. I have seen some high-key shots that were attractive and effective and do appreciate the skill and art of the photographers who can pull that off.

Specular high-lites might deserve to be blown out. Not the point of my response. I’ll just say it one more time and then go away … if it is clipped (by a sharp knee response curve … due to sensor saturation or A/D saturation or any saturation link in the chain) it is GONE!

mike

Oct 6, 2009

In article <hadpc1$8up$>,
says…

So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

But unlike a hair-cut it never grows back. More of an amputation methinks…

Mike

john

Oct 6, 2009

On Tue, 6 Oct 2009 18:27:10 -0400, "Charles"
wrote:

Digital clipping is almost never "saturation of the sensor". Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

And what difference would that make? There is no sharper knee than one imposed by basic mathematics. 2^8 = 256, is a simple example. With 8 bits, the maximum value is 255, base 10, with NO exceptions possible. You actually help to make the case that over-exposed digital shots guarantee lost information in the bright portions of the scene.

I continue to believe that exposing to the right is perpetuated by folks with limited experience and knowledge. They are perhaps into the dark parts of scenes and don’t understand dynamic range. Many of us are more greedy and want details at both ends of the luminosity range.

Hey, blow those high-lites out! If that is the intended message of a given scene, go for it. I don’t care for over-exposed shots … they are just not my thing. I have seen some high-key shots that were attractive and effective and do appreciate the skill and art of the photographers who can pull that off.

Specular high-lites might deserve to be blown out. Not the point of my response. I’ll just say it one more time and then go away … if it is clipped (by a sharp knee response curve … due to sensor saturation or A/D saturation or any saturation link in the chain) it is GONE!

The "expose to the right" approach isn’t about blowing highlights, or otherwise pegging the sensors. It’s about not leaving too big a gap on the right side of the histogram so that the quantified & digitized brightness readings cover a larger range from min to max. That’s where your dynamic range comes from in a digital camera. Perhaps it would be clarifying to realize that digital light sensors read light linearly, not on a curve, and at discrete levels. Also, white balance adjustments are channel multipliers, not curves.

Don’t like "overexposed" images? Counteradjust the exposure in post. That’s the second half of the technique anyway. It’s easy, and you’ll find that at a given ISO you’ll end up with less noise in the final image.

floyd

Oct 6, 2009

Paul Furman wrote:

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping.

The brightest part will still show at *exactly* the
same
place.

Maybe for contrast (though I doubt it) but WB makes a big difference. I just tested at 25K & 100K, the highlights are completely different. I’m looking at split RGB histograms btw.

That is exactly the point I *am* making. WB changes the histogram in a useful way. The Luminous-Landscape
article did not talk about WB at all. They discussed
changing the camera’s setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue.

And if you doubt that the contrast setting will not change the histogram as stated, *try* *it*. I gave an step by
step description of a very easy way to show exactly what does and does not happen. Why argue from supposition when you could actually learn something about photography…

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Doug McDonald

Oct 6, 2009

Charles wrote:

I continue to believe that exposing to the right is perpetuated by folks with limited experience and knowledge. They are perhaps into the dark parts of scenes and don’t understand dynamic range. Many of us are more greedy and want details at both ends of the luminosity range.

Hey, blow those high-lites out! If that is the intended message of a given scene, go for it. I don’t care for over-exposed shots … they are just not my thing. I have seen some high-key shots that were attractive and effective and do appreciate the skill and art of the photographers who can pull that off.

Specular high-lites might deserve to be blown out. Not the point of my response. I’ll just say it one more time and then go away … if it is clipped (by a sharp knee response curve … due to sensor saturation or A/D saturation or any saturation link in the chain) it is GONE!

Again, you simply don’t understand.

Let me explain. Say you are doing a landscape of a very
cloudy scene, with not a trace of sun visible, with high level clouds blocking the sun, so it does not shine on lower level clouds. The contrast in the sky is still moderately high. The low key lighting also makes contrast in the
land part of the scene low. The whole affair is low contrast.

If you expose by TTL light meter, normally, it will expose so that the average of the scene is 18% gray. The highlights, that is, the brightest clouds, will not be clipped, in fact they will be well below that. So you expose to the right so that the brightest clouds are just below clipping. This gets more photons, ergo, better S/N.

Now remove the high level clouds. The sun is shining on the lower level clouds and is very, very, very bright. But the foreground is in shade! You want to not clip the clouds. The TTL meter will likely want to clip them. So you
are careful and expose to the right to avoid clipping the clouds.

Now a little bit of sun shines of the foreground, on
a waterfall. If you use the same exposure as the paragraph above, the specular highlights on the water will clip.
You may very well actually WANT that to happen, so you
are careful to let it.

You ALWAYS want to expose to the right, given enough light that you don’t need a too-long exposure and blurring. Indeed, of course, you may want to clip specular highlights.

The idea is that this is the correct way, the photographer simply has to understand how to get it right.

The only time you don’t want to expose to the right is
if you are already at ISO 1600 or 3200 and still there
is too little light to avoid blurring if you do.

Doug McDonald

abo mahab

Oct 7, 2009

Keys to Happiness

Happiness is the only goal on earth that all people without exception are seeking to attain. Believers and unbelievers alike seek to be happy, but each party is using different methods.

However, only believers can achieve genuine happiness. All forms of happiness attained without a firm belief in God, the Almighty, are mere illusions.

The following are tips for the attainment of happiness:

1. Know that if you do not live within the scope of today, your thoughts will be scattered, your affairs will become confused, and your anxiety will increase. These realities are explained in the following hadith:

“When you are in the evening, do not expect to see themorning, and when you are in the morning, do not expect to see the
evening.” (Saheeh Al-Bukhari)

2. Forget the past and all that it contained, focus on the present.

3. Do not completely preoccupy yourself with the future and then discard the present. Be balanced in life, prepare yourself adequately for all situations.

4. Do not be shaken by criticism; instead, be firm. Be sure that in proportion to your worth, the level of people’s criticism rises. Also, make good use of criticism in discovering your shortcomings and faults, and let it drive you toward self-improvement.

5. Have complete faith in God and perform good deeds; these are the ingredients that makeup a good and happy life.

6. If you desire peace, tranquility, and comfort, you can find it all in the remembrance of God.

7. You should know with certainty that everything that happens, occurs in accordance with the divine decree.

8. Do not expect gratitude from anyone.

9. Train yourself to be prepared for the worst possibility.

10. Perhaps what has happened is in your best interest, even though you may not comprehend how that can be so.

11. Everything that is decreed for the believer is the best for him.

12. Enumerate the blessings of God and be thankful for them.

13. Remember that you are better off than many others.

14. Relief comes from one hour to the next. Indeed, with each difficulty there is relief.

15. In both times of hardship and ease, one should turn to supplication and prayer, either patiently contented or thankful.

16. Calamities should strengthen your heart and reshape your outlook in a positive way.

17. Do not let trivialities be the cause of your destruction.

18. Always remember that your God is Oft-Forgiving.

19. Assume an easy-going attitude and avoid anger.

20. Life is bread, water, and shade; so do not be perturbed by a lack of any other material thing.

“And in the heaven is your providence and that which you are promised.” (Quran 51:22)

21. A daunting evil that seemingly will happen usually never occurs.

22. Look at those who have more afflictions and be grateful that you have less.

23. Bear in mind the fact that God loves those who endure trials with steadfastness, so seek to be one of them.

24. Constantly repeat those supplications that the Prophet (may God praise him) taught us to say during times of hardship.

25. Work hard at something that is productive, and cast off idleness.

26. Do not spread rumors and do not listen to them. If you hear a rumor inadvertently, do not believe it.

27. Know that your malice and your striving to seek revenge are much more harmful to your health than they are to your antagonist.

28. The hardships that befall you atone for your sins, if you endure with patience.

Source::: www.islamreligion.com

floyd

Oct 7, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

As I noted, the *shape* of the curve has absolutely
nothing to do with setting exposure.
If you check the shape, what you learn is the tonal
distribution within the recorded dynamic range, not the
range itself.

For the Canon 30D, that is incorrect. True, you do learn the shape.

Stop guessing, and actually try it in a way that is
definitive. If you don’t come up with the correct
answers, describe precisely what you did and we can work out what is wrong with the technique or the analysis of
it.

But at contrast levels (as described in the camera setup) of -3 or 0-, you **DO** learn at least the high end of the contrast range. Do you understand this? That is, at -3 or -4, there is enough detain in the in-camera histogram to tell, quite accurately, how close you are to overload of the raw file. At -2 or higher, the compression of the (internal) jpeg from which the histogram is made makes telling that problematic.

You are admitting that it *doesn’t* change the exposure
level at all!

Yes, for some scenes it might (but cannot in others)
push more of the area under the graph towards to right
at the right most edge, but it will *not* change where
the brightest part of the graph is located in relation
to the right edge, which is the *only* point of any
significance for setting exposure.

Let’s reiterate those two points:

1) The *only* characteristic of the histogram that
is significant for setting exposure is the location
of the right edge of the graphed data in relationship
to the absolute right edge of the graph.

2) In-camera contrast adjustment does not change the
location of the right most edge of the graphed data.

If you have difficulty seeing when the graph is at the
right edge, the "corrective action" is to learn how to read the graph, not a camera adjustment! Indeed,
pushing more of the area closer to the right makes it,
in common instances, *more* difficult! What you want to watch for is a spike at the right end, and then back off until there is none. That is actually *harder* to see
when there are higher data counts on the right side. It is very easy to see if the graphed data amounts to a one pixel horizontal line approaching the right side.

The above assumes no part of the image should have blown highlights…; in fact it is not uncommon to *want* some areas to blow out, and in that case the histogram is
useless anyway! Use a blinking highlight display
instead. And again, contrast settings will not have
*any* effect at all on the blinking highlight display.
None! (Even with a Canon 30D! Assuming it has a
highlight display…)

The histogram shape, and thus the
in-camera contrast setting, is useless and has no effect at all on the camera raw data that is later manipulated
with post processing.

At settings more than -3, that is true always, and yes,
it has no effect on the raw file.

At any settings, -3, -5, or +5… It is useless in terms of setting the exposure, because it does not affect the
raw data *or* the location of the histogram’s right edge.

It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

With respect, you are wrong. The in-camera histogram will help you adjust your exposure if the first one is not right.

You need to learn to read a little better Steven.
The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

THAT LAST PARAGRAPH IS INCORRECT FOR THE CANON 30D!

Try it and see!

Changing the in-camera contrast setting DOES change how close the graph approaches the right side. REALLY!! I’ve tried it many times. Changing the in-camera contrast setting seems to expand or contract the histogram about some point in the middle. I’m not saying its the exact center, I have not tried telling. I could do this, but have not.

I realize you have not done this. If you did you might
have a better understanding of how it works.

It changes the area under the graph, exanding or
contracting it from the left side. It does not change
the location of the right end of the data. That is, it
does not move the right edge of the data horizontally.
It may move data from 1 stop left of the edge closer to
the edge, but the *edge* stays where it was.

All you have to do is experiment with a single point source of light against a less well light background, and all of this should become obvious.

Have YOU examined the histogram on a Canon 30D?

If you have not, I suggest that you preface your remarks with "on the cameras I have actually personally tested i.e.
[list of cameras] …".

It is obvious from your description that you have not
learned the fine points of reading a histogram (which is typical of most photograhers, so do not take that as an
insult), and have not actually experimented with a 30D
or any other camera to learn what is actually happening.

Again, contrast both in theory and in the practical
application of theory to a digital camera, changes slope of the curve, not the range it covers.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Doug McDonald

Oct 7, 2009

Floyd L. Davidson wrote:

Let’s reiterate those two points:

1) The *only* characteristic of the histogram that
is significant for setting exposure is the location
of the right edge of the graphed data in relationship
to the absolute right edge of the graph.

2) In-camera contrast adjustment does not change the
location of the right most edge of the graphed data.

If you have difficulty seeing when the graph is at the
right edge, the "corrective action" is to learn how to read the graph, not a camera adjustment!

You are simply wrong.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I took exactly the same picture with the contrast set
at -4 and it set at 0 (and in between). The camera was set on manual, the f/number and time were the same.
Upon inspection in the computer, the raw files were the same. Neither file was overexposed. The scene had a white card in it, no specular anything.

Now lets see what I saw on the camera histogram. With the -4 contrast setting, the beak due to the white card is well away from the right edge, and the right edge of the red channel is (I’m looking right now!) is about 1mm from the right edge, while the blue and green are farther to the left, at roughly 2 amd 3mm to the left. One mm is about 6 pixels on the view screen.

Now, looking at th histogram with the 0 (higher) contrast setting is different (REMEMBER … I’m looking at it right now!). The central part of the histogram is expanded, with the "node" point where it expands about being 40% of the way from the left. The top and bottom parts are compressed. The top part is so compressed that the red channel bumps into the right edge of the histogram display area. There is a tiny space between the top of the green and the right edge. The top of the blue is about 1 mm from the edge.

Thus, using the 0 in-camera contrast setting I would have not seen the gap between the red channel and the right of the histogram, and would have thought it overexposed.

Got it?

NOTE: if you wish to continue, tell me the last four digits of your Canon 30D serial number. Mine is 3965.

Doug McDonald

Paul Furman

Oct 7, 2009

mike wrote:

In article <hadpc1$8up$>,
says…

So, expose to the right if you can afford lost high-lites … and I do mean to emphasize LOST. Like a hair-cut, clipped is gone.

But unlike a hair-cut it never grows back. More of an amputation methinks…

http://www.telegraph.co.uk/news/newstopics/howaboutthat/6266 097/Pensioner-grows-new-skull.html

-just kidding but ‘never say never’ <g>

Doug McDonald

Oct 7, 2009

Floyd L. Davidson wrote:

It is obvious from your description that you have not
learned the fine points of reading a histogram (which is typical of most photograhers, so do not take that as an
insult), and have not actually experimented with a 30D
or any other camera to learn what is actually happening.

Let me say it again: I have … AND HAD BEFORE I EVER POSTED … actually tried it on my very own Canon 30D and I DO know the fine points of reading a histogram on this camera.

You are wrong to insult me by suggesting otherwise.

Finally I will say this: **IF** the in-camera histogram had say 32768 pixels actually visible in it (8 times more than the camera’s 12 bit ADC) the you would be right,
at least if I had a good magnifier on me. I would,
in those circumstances, still be able to see the
"daylight" between the top of the scrunched up histogram at the contrast = 0 setting and the top of the screen. But with the very limited resolution it actually has (maybe 150 pixels),
what I said in the previous post is correct.

Let me say this once more: I have been doing this histogram peeping for years, and to be useful the contrast setting really DOES have to be at -4 or -3. This is experience with this very camera speaking. I do LOTS of landscape shots at low ISO where I intend all the cloud detail and all the shadow detail to be visible in the final print. This requires getting the exposure EXACTLY right for best effect. I KNOW how to use the histogram to do this. And I KNOW how not to do it (i.e. setting contrast > -3 in the camera is a no-no.)

TRY IT!! In your very own Canon 30D.

Doug MCDonald

JPS

Oct 7, 2009

Porte Rouge wrote in news:eaf6a46b-3ba3-4ba1-
:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

They’re not really over-exposed, they have simply put your highlights on a tone curve which makes the colors look pale.

The whole point of you "exposing to the right" is to increase the signal- to-noise ratio. The "number of tones" explanation often given is incorrect. All digital cameras have too much noise at all tones to be limited by numbers of tones, at least in the RAW data. The number of tones in your output are unrelated to the number of tones in the RAW exposure; you do not lose all you’ve gained when the software darkens the image.

Mike Russell

Oct 7, 2009

This discussion transcended any technical merit long ago, but here’s my two cents.

For both Nikon and Canon the histogram is based on converted channel RGB values, not raw sensor values.
http://www.brisk.org.uk/photog/histo5.html
—
Mike Russell – http://www.curvemeister.com

Mike Russell

Oct 7, 2009

On Sun, 4 Oct 2009 17:25:57 -0700 (PDT), Porte Rouge wrote:

Wow, good stuff. I had to run out and get my camera and check the settings. I don’t understand what he says about the white balance. I have it set on auto and have ignored it when shooting RAW. Should I adjust it for each lighting condition when I shoot and this will give me a truer histogram?

Setting a more correct white balance may give a more accurate histogram, but this is relying too much a coarse measurement.

When in doubt, give up another half stop or more past the point where the "blinkies" stop, or bracket your exposure as insurance against blown highlights.
—
Mike Russell – http://www.curvemeister.com

floyd

Oct 7, 2009

"Charles" wrote:

Digital clipping is almost never "saturation of the sensor". Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

And what difference would that make?

The statement was that digital clipping was due to
saturation of the sensor. The fact is, it’s not.

And note that if it were there would be a significantly
different set of characteristics to apply, the ADC does
saturate with the mathematical precision you note below, while the analog electronic sensor does not.

There is no sharper knee than one
imposed by basic mathematics. 2^8 = 256, is a simple example. With 8 bits, the maximum value is 255, base 10, with NO exceptions possible. You actually help to make the case that over-exposed digital shots guarantee lost information in the bright portions of the scene.

Nobody with an ounce of understanding would deny that,
so why do you find it worth noting that I ‘actually
help’ make that case? Of course I did!

I continue to believe that exposing to the right is perpetuated by folks with limited experience and knowledge. They are perhaps into the dark parts of scenes and don’t understand dynamic range. Many of us are more greedy and want details at both ends of the luminosity range.

You must not understand dynamic range then, given that
statement! The entire concept of "Expost To The Right" is based on maximizing captured dynamic range. It is
*precisely* a way to get maximum "details at both ends".

Hey, blow those high-lites out! If that is the intended message of a given scene, go for it. I don’t care for over-exposed shots … they are just not my thing. I have seen some high-key shots that were attractive and effective and do appreciate the skill and art of the photographers who can pull that off.

Specular high-lites might deserve to be blown out. Not the point of my response. I’ll just say it one more time and then go away … if it is clipped (by a sharp knee response curve … due to sensor saturation or A/D saturation or any saturation link in the chain) it is GONE!

Gee whiz, that’s like arguing that rocks are "hard". And of course that is exactly why people use the Expose
To The Right method.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 7, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

Let’s reiterate those two points:
1) The *only* characteristic of the histogram that
is significant for setting exposure is the location
of the right edge of the graphed data in relationship
to the absolute right edge of the graph.
2) In-camera contrast adjustment does not change the
location of the right most edge of the graphed data.
If you have difficulty seeing when the graph is at the
right edge, the "corrective action" is to learn how to read the graph, not a camera adjustment!

You are simply wrong.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I HAVE ACTUALLY DONE THIS WITH MY CAMERA.

I took exactly the same picture with the contrast set
at -4 and it set at 0 (and in between). The camera was set on manual, the f/number and time were the same.
Upon inspection in the computer, the raw files were the same. Neither file was overexposed. The scene had a white card in it, no specular anything.

Now lets see what I saw on the camera histogram. With the -4 contrast setting, the beak due to the white card is well away from the right edge, and the right edge of the red channel is (I’m looking right now!) is about 1mm from the right edge, while the blue and green are farther to the left, at roughly 2 amd 3mm to the left. One mm is about 6 pixels on the view screen.

Now, looking at th histogram with the 0 (higher) contrast setting is different (REMEMBER … I’m looking at it right now!). The central part of the histogram is expanded, with the "node" point where it expands about being 40% of the way from the left. The top and bottom parts are compressed. The top part is so compressed that the red channel bumps into the right edge of the histogram display area. There is a tiny space between the top of the green and the right edge. The top of the blue is about 1 mm from the edge.

Thus, using the 0 in-camera contrast setting I would have not seen the gap between the red channel and the right of the histogram, and would have thought it overexposed.

Got it?

I got that it you still haven’t done anything to
determine what the distinction is.

Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.

How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Use *both* settings of contrast and you’ll find that
either way, the *same* exposure is what will put the
peak of the histogram exactly on the right edge of the
graph. Which is to say that it is no more or less accurate with either contrast setting! You get the exact same
exposure either way.

As I noted previously, you clearly have not learned the
fine points of reading a histogram, and when you say
that one condition above would be easier to miss than
another, it just demonstrates exactly that point. Yes,
with one given scene you might be more likely, with just a quick glance, to miss what is there than you would
with a different contrast setting. But the converse is
also true, in that with some different scene it would be the *other* contrast setting that makes is more/less
likely to see the precision.

The point was that the exposure you get by using the
histogram is *not* going to be any more or less
*accurate* due to changing the in-camera contrast
settings.

That is as opposed to changing the White Balance, which
in fact *will* change the exposure setting derived from
the histogram; and setting the WB in one particular way
will make result in more "accurate" exposures, which is something not gained by chaning the contrast.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 7, 2009

Mike Russell wrote:

This discussion transcended any technical merit long ago, but here’s my two cents.

That is not true. The discussion is about whether or
not there is merit to setting an in-camera contrast
setting to get more a more accurate histogram derived
exposure. A Luminous Landscape article said you would,
and people believe it. It is not valid.

On the other hand, others want to know why, if the above is not valid, it is claimed that changing the WB setting does have that effect.

There *is* technical merit in learning how to adjust a
camera to get accurate exposure.

For both Nikon and Canon the histogram is based on converted channel RGB values, not raw sensor values.

That is basically true of all DSLR’s. It has
"problems", but it works. The idea that raw data could be used is not likely to be valid, and while it sounds
good in simple terms, the complex histogram that would
result just would not be as useful!

What I would like to see is a separate interpolation of
the raw data to provide a histogram, as opposed to the
one used to provide the JPEG image for preview display.
I like both having a useful preview image (one that is
not a sickly green) *and* an accurate histogram (which
produces a green tinge if used for a JPEG too).

http://www.brisk.org.uk/photog/histo5.html–
Mike Russell – http://www.curvemeister.com

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Doug McDonald

Oct 7, 2009

Floyd L. Davidson wrote:

I got that it you still haven’t done anything to
determine what the distinction is.

Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.

How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Quite a bit … at contrast setting 0. I don’t have my camera with me right now, so I can;t comment wuantitatively.

Use *both* settings of contrast and you’ll find that
either way, the *same* exposure is what will put the
peak of the histogram exactly on the right edge of the
graph. Which is to say that it is no more or less accurate with either contrast setting! You get the exact same
exposure either way.

I will be extra-careful and actually try this before commenting.

I can’t extrapolate from my previous tests, because a 1/3 stop increase in exposure, will result in
clipping of the red channel, and at contrast setting -4
will move the red channel all the way to the top.. A 1/3 stop decrease (at contrast setting -4) will move all three channels to the left a clearly visible amount. However, I still make MY point an negate yours:

my point is that at contrast setting -4, I can see that there is no clipping, whereas at contrast setting 0, I cannot see that … and in fact there is no clipping. This negates your point without doing the "decrease exposure" test.

But I will do the decrease exposure test to see if, at
contrast level 0 (and I will try -2 also), it will move the red channel away from the absolute right edge of the histogram.

But, still, with what I have said YIOU POINT IS NEGATED.

You keep saying I don’t understand … but I **DO**

READ WHAT I JUST SAID!!!

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not. That’s teh bottom line. Can;t you see this?

Now, when I do your test, reducing 1/2 stop, if I CAN
see that red does not clip, then you have made the point that using contrast setting 0 is in fact only 1/2 stop WORSE for getting the highest possible unclipped exposure than using contrast setting 0.

BUT … my point is made already.

LET ME REPEAT, TRY TO UNDERSTAND:

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not.

Doug MCDonald

Doug McDonald

Oct 7, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

I got that it you still haven’t done anything to
determine what the distinction is.

Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.

How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Quite a bit … at contrast setting 0. I don’t have my camera with me right now, so I can;t comment wuantitatively.

one more thing: I told you the last four digits of my Canon 30D’s serial number.

If you want to have any standing in this little Usenet flamefest, you should at least tell me the last four digits of YOUR Canon 30D serial number. At least, the number for the one you try it on!

Do you have access to a 30D to try it on? Have you done so?

Doug McDonald

Paul Furman

Oct 7, 2009

John Sheehy wrote:

Porte Rouge wrote

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

They’re not really over-exposed, they have simply put your highlights on a tone curve which makes the colors look pale.

The whole point of you "exposing to the right" is to increase the signal- to-noise ratio. The "number of tones" explanation often given is incorrect. All digital cameras have too much noise at all tones to be limited by numbers of tones, at least in the RAW data. The number of tones in your output are unrelated to the number of tones in the RAW exposure; you do not lose all you’ve gained when the software darkens the image.

OK, the noise is more the reason but posterizing can be a problem in dark areas… raising shadows in post for the deepest shadows, and in skies where the color pallet is very limited. Doesn’t the noise level follow this same principle? Or is there an unrelated reason for the noise levels paralleling tone counts?

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

floyd

Oct 7, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

I got that it you still haven’t done anything to
determine what the distinction is.
Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.
How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Quite a bit … at contrast setting 0. I don’t have my camera with me right now, so I can;t comment wuantitatively.

Use *both* settings of contrast and you’ll find that
either way, the *same* exposure is what will put the
peak of the histogram exactly on the right edge of the
graph. Which is to say that it is no more or less accurate with either contrast setting! You get the exact same
exposure either way.

I will be extra-careful and actually try this before commenting.
I can’t extrapolate from my previous tests, because a 1/3 stop increase in exposure, will result in
clipping of the red channel, and at contrast setting -4
will move the red channel all the way to the top.. A 1/3 stop decrease (at contrast setting -4) will move all three channels to the left a clearly visible amount. However, I still make MY point an negate yours:

Exactly. No matter what the constrast adjustment, a
change in exposure moves all three channels by the same
amount, until one clips. Clipping happens with the same channel and at the same exposure no matter what your
contrast setting is.

my point is that at contrast setting -4, I can see that there is no clipping, whereas at contrast setting 0, I cannot see that … and in fact there is no clipping. This negates your point without doing the "decrease exposure" test.

Okay, if that is true, try a scene with different
illumination. Try looking at a high key scene, then try looking at a low key scene. If low contrast helps with
one, high contrast will help with the other!

The point is still the same, contrast settings do *not*
affect the exposure. Your ability to read a histogram
accurately is not of concern, and is variable not only
with the contrast setting but also with the type of
illumination.

But I will do the decrease exposure test to see if, at
contrast level 0 (and I will try -2 also), it will move the red channel away from the absolute right edge of the histogram.

If it doesn’t, you are over exposing. And the point is
that at contrast setting of -4, -2 and 0 the proper
exposure is always going to be the same.

But, still, with what I have said YIOU POINT IS NEGATED.

Not even close.

You keep saying I don’t understand … but I **DO**

READ WHAT I JUST SAID!!!

I have.

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not. That’s teh bottom line. Can;t you see this?

Switch between high key lighting and low key lighting
and tell me that it low contrast is an improvement for
both! 🙂

You still miss the point that the proper exposure with
high or low contrast settings is exactly the same. If
you read the histogram carefully, it makes no difference what the contrast setting is. And high or low contrast
may have exactly the opposite effects on ease of reading the histogram for different scenes.

The answer is *not* setting contrast to something low,
it’s learning how to read a histogram with precision!

Now, when I do your test, reducing 1/2 stop, if I CAN
see that red does not clip, then you have made the point that using contrast setting 0 is in fact only 1/2 stop WORSE for getting the highest possible unclipped exposure than using contrast setting 0.

There should not be any change at all in where you get
correct exposure, *if* you read the histogram properly.
The contrast setting does *not* change the exposure at
which the maximum brightness hits the right side of the
graph!

What changing to low contrast will do is move more of
the data points closer to the right end of the graph,
and for a low key scene that may help to read the graph
while for an high key scene it might make it more
difficult (because you cannot see the spike when
clipping just begins, making perfect look identical to
half a stop over exposed).

BUT … my point is made already.

LET ME REPEAT, TRY TO UNDERSTAND:

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not.

Clipping begins at exactly the same place, and it either has a data point at that level, or it doesn’t. Your
point seems to be that you cannot closely examine a
histogram graph for appropriate detail. (I’m no spring
chicken myself, and wear bifocal glasses; though I am
very near sighted and sometimes just take the glasses
off to closely examine something like a histogram chart. Is it possible that your eyesight does not allow seeing
fine detail up close?)

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 7, 2009

Doug McDonald wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

I got that it you still haven’t done anything to
determine what the distinction is.

Do the same thing, except bracket the exposure by 1/2
and fstop, so that you can see the differences.

How far does 1/2 an fstop move that red channel graph,
compared to the 1mm (6 pixel) change you have above?

Quite a bit … at contrast setting 0. I don’t have my
camera with
me right now, so I can;t comment wuantitatively.

one more thing: I told you the last four digits of my Canon 30D’s serial number.

If you want to have any standing in this little Usenet flamefest, you should at least tell me the last four digits of YOUR Canon 30D serial number. At least, the number for the one you try it on!

Do you have access to a 30D to try it on? Have you done so?

What logical basis do you have for insisting that your
Canon 30D is different than every other DSLR?

I’ll grant that a model that old probably does not have
the nicest histogram display compared to newer cameras,
but rest assured that the contrast settings have *exactly* the same effect as they do on a Nikon D3, or any of the
more recent Canon models either.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Doug McDonald

Oct 7, 2009

Exactly. No matter what the constrast adjustment, a
change in exposure moves all three channels by the same
amount, until one clips. Clipping happens with the same channel and at the same exposure no matter what your
contrast setting is.

in the raw file YES, on the on-camera histogram,
the resolution is too awful at contrast setting to be able to tell.

my point is that at contrast setting -4, I can see that there is no clipping, whereas at contrast setting 0, I cannot see that … and in fact there is no clipping. This negates your point without doing the "decrease exposure" test.

Okay, if that is true, try a scene with different
illumination. Try looking at a high key scene, then try looking at a low key scene. If low contrast helps with
one, high contrast will help with the other!

The point is still the same, contrast settings do *not*
affect the exposure.

Nor the raw file … but they DO change the on-camera
histogram of a Canon 30D … and my point is that at an in-camera contrast setting 0, the utility of the histogram is such that you can’t get within 1/3 or 1/2 stop of clipping
(in the raw file) and be sure you are OK, while at
a camera setting of -4 you can tell.

Your ability to read a histogram
accurately is not of concern, and is variable not only
with the contrast setting but also with the type of
illumination.

It may vary with color temperature

But I will do the decrease exposure test to see if, at
contrast level 0 (and I will try -2 also), it will move the red channel away from the absolute right edge of the histogram.

If it doesn’t, you are over exposing.

Uh, NO NO NO … NO NO NO … at the CURRENT exposure it is NO OVER EXPOSING and at contrast setting 0 the histogram says it IS OVEREXPOSING
i.e. the histogram is wrong.

And the point is
that at contrast setting of -4, -2 and 0 the proper
exposure is always going to be the same.

of course the proper exposure will be the same … it is just that at -4 I can tell from the histogram, at
0 I can’t.

But, still, with what I have said YIOU POINT IS NEGATED.

Not even close.

You keep saying I don’t understand … but I **DO**

READ WHAT I JUST SAID!!!

I have.

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not. That’s teh bottom line. Can;t you see this?

Switch between high key lighting and low key lighting
and tell me that it low contrast is an improvement for
both! 🙂

That I didn’t do … it was low key, and the highest
intensity area was a large area of white card.

You still miss the point that the proper exposure with
high or low contrast settings is exactly the same.

I do not miss the point. Of course the proper exposure is the same … it is not EXPOSURE I am talking about … IT IS THE ON CAMERA HISTOGRAM AND ITS REFLECTION, CORRECT OR INCORRECT, of the exposure.

If
you read the histogram carefully, it makes no difference what the contrast setting is.

INCORRECT!! READ WHAT I SAID!!!

There should not be any change at all in where you get
correct exposure, *if* you read the histogram properly.
The contrast setting does *not* change the exposure at
which the maximum brightness hits the right side of the
graph!

INCORRECT!!!

What changing to low contrast will do is move more of
the data points closer to the right end of the graph,
and for a low key scene that may help to read the graph
while for an high key scene it might make it more
difficult (because you cannot see the spike when
clipping just begins, making perfect look identical to
half a stop over exposed).

BUT … my point is made already.

LET ME REPEAT, TRY TO UNDERSTAND:

In a condition where there is NO CLIPPING a contrast setting -4 histogram allows me to see that, while one of zero does not.

Clipping begins at exactly the same place, and it either has a data point at that level, or it doesn’t. Your
point seems to be that you cannot closely examine a
histogram graph for appropriate detail.

I can examine the histogram all day with a microscope,
and at contrast setting 0, THE DETAIL IS NOT GOOD ENOUGH TO TELL.

If the camera had a three foot wide histogram display,
with 32000 pixels, you would indeed likely be correct!

But **I** am talking real world on a real camera.

I suggest you try a REAL Canon 30D.

Doug McDonald

DRS

Oct 7, 2009

"Floyd L. Davidson" wrote in message

[…]

The point is still the same, contrast settings do *not*
affect the exposure.

Since nobody has said it does why don’t you slow down and pay attention to what is being said?

What is being said is that where manufacturers draw the histogram settings from the compressed JPEG instead of the Raw image, lowering the contrast setting will render the histogram more accurately (closer to the Raw). The claim is that this more accurate histogram *subsequently* enables the photographer to make more accurate adjustments to the exposure.

Check out the images under the heading "Contrast adjustment" on this page: http://www.dpreview.com/reviews/CanonEOS30D/page13.asp. The luminosity histogram expands left and right as you increase the contrast. If you were to judge by the +4 histogram you would think the image was clipping both highlights and shadows but this is not the case.

If the histogram at -4 is in fact more accurate than the histogram at 0 (the Canon default) then the photographer in fact has greater room for exposure compensation to the right than the histogram at contrast setting 0 indicates. For those wishing to compensate to the right this is useful information. What the photographer *subsequently* chooses to do to the exposure is another discussion entirely.

JPS

Oct 7, 2009

Paul Furman wrote in september.org:

OK, the noise is more the reason but posterizing can be a problem in dark areas…

The only cameras I know of with even a hint of RAW posterization are the Pentax K10D, which would profit from 13 bits instead of 12 at ISO 100 (not for 200 or higher), the Sony A900 also with a need for 13 bits at base, and the D3X when in 12-bit mode. These are only on the fringe of posterizing.

raising shadows in post for the deepest shadows, and in skies where the color pallet is very limited. Doesn’t the noise level follow this same principle? Or is there an unrelated reason for the noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most likely caused by the math used in the converter, and nothing else. Of course, JPEG compression does some posterization of its own, especially if you use too much NR and it starts blocking up.

JPS

Oct 7, 2009

"Charles" wrote in
news:hagg86$ugf$:

Digital clipping is almost never "saturation of the sensor". Unless you are shooting at the base ISO
clipping is saturation of the Analog-Digital-Converter
(ADC) by sensor output that is greater than the maximum
ADC input.

And what difference would that make? There is no sharper knee than one imposed by basic mathematics. 2^8 = 256, is a simple example. With 8 bits, the maximum value is 255, base 10, with NO exceptions possible. You actually help to make the case that over-exposed digital shots guarantee lost information in the bright portions of the scene.

Exposure to the right is usually given as advice for RAW shooting. The RAW data usually clips well above the level where a JPEG would clip it, and the trailing color channels, usually red or blue, are less sensitive and blow out in the RAW data much higher than in a JPEG. For red, there is typically 2 stops more of highlight headroom in the red channel with daylight WB. For the blue channel, 3 stops with tungsten WB.

Red is actuall being shot at double the ISO in daylight, and blue at 8x the ISO in incandescent light!

I continue to believe that exposing to the right is perpetuated by folks with limited experience and knowledge. They are perhaps into the dark parts of scenes and don’t understand dynamic range. Many of us are more greedy and want details at both ends of the luminosity range.

That depends on how and why ETTR is used. I don’t see a whole lot of people recommending the act of blowing out the highlights to obtain ETTR. It is something you can do when you can; when you know it won’t cause clipping. The advantage in SNR is tremendous. The shot noise, relative to signal, decreases when you increase absolute exposure (measured in absolute sensor exposure, ISO setting is irrelevant to shot noise except for potential clipping). The read noise decreases, relative to signal, too, especially when you are using Canon-style CMOS where the read noise comes mainly at a later stage in the signal chain, and are very close in intensity at all low ISOs (up to 400 or 800). With such cameras, you get a huge decrease in read noise (relative to signal) by using a higher ISO, if it doesn’t cause clipping, without even increasing the absolute exposure.

Hey, blow those high-lites out!

You’re being ridiculous. You are completely dismissing the idea of ETTR, based on a reckless strawman. There is no connection between the idea of using ETTR when it is feasible, and using it haphazardly.

If that is the intended message of a
given scene, go for it. I don’t care for over-exposed shots … they are just not my thing. I have seen some high-key shots that were attractive and effective and do appreciate the skill and art of the photographers who can pull that off.

Specular high-lites might deserve to be blown out. Not the point of my response. I’ll just say it one more time and then go away … if it is clipped (by a sharp knee response curve … due to sensor saturation or A/D saturation or any saturation link in the chain) it is GONE!

If it is. It may not be, however, if you shoot RAW.

For JPEGs, it is pretty trivial to set the camera up to produce low- contrast JPEGs, and then use darkening gamma correction to pull the tones back down to saturated colors. Low-contrast usually allows more of the RAW headroom to be used in the JPEG, and makes the highlight clipping indicator more accurate in most cases. The only time it not clipping when something is really clipped in the RAW, IME, is when the highlight is bright blue against a dark background, because a weighted RGB histogram gives very little weight to blue.

JPS

Oct 7, 2009

(Floyd L. Davidson) wrote in
news::

The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

The left side of the histogram is only an artifact of conversion, and the arbitrary curve used on the X axis. The top stops are usually made to look like each stop takes the same percentage of the entire histogram, but the left side suddenly turns linear, creating a left edge. If the spacing used on the right side were used on the left, the left side of the histogram would never reach black; it would go on to infinity.

Talking about the left edge of a histogram is usually gibberish. It is SNR which determines the quality of RAW shadows; not histogram positions.

Wilba

Oct 8, 2009

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the left, so that’s a waste of time. To avoid having the deep colours washed out, you need to make use of the full tonal range available in the image. If you have done a good job of exposing to the right, your highlights will be pretty much where they need to be. So then all you need to do is raise the black point (e.g. using the Levels dialog in Photoshop), so that the dark tones in the scene end up as dark tones in the image. If you are using the Levels dialog in Photoshop, while you drag the black (or white) point slider, press the Alt key to see which pixels are clipped (or blown).

(The following relates to my experience with a Canon 450D. YMMV.)

There are two parts to exposing to the right – levels in the image and saturation of photosites. Whether you are shooting JPEG or raw, the camera’s histogram display shows you the levels in a JPEG produced from the raw data, so the shape of the histogram curve depends on your settings for sharpness, contrast, saturation, colour tone, etc.

If you are shooting JPEG, all you can do is avoid piling up the histogram on the right, which prevents gross areas of blown highlights in the image.

If you are shooting raw, you can overexpose (beyond the point at which the histogram curve touches the right boundary), by about two steps and still produce an image from the raw without blown highlights. IOW, the headroom between blown highlights in the JPEG and saturation of the photosites is about two steps (in my experience, with the JPEG settings I use).

So if you are bracketing for the best possible exposure, go at least two steps over what the histogram tells you is "correct". The maximum possible dynamic range occurs at the point where photosites in the highlights begin to saturate.

In everyday raw shooting, you can be quite relaxed about having a small spike on the right of the histogram – that’s actually a good thing.

floyd

Oct 8, 2009

John Sheehy wrote:

(Floyd L. Davidson) wrote in
news::

The histogram will help you adjust your exposure, and
that is *exactly* what I have said. What I’ve also said is that changing the in-camera contrast setting does not change the histogram in any way that will affect
exposure. It does *not* change how close the graph approaches the right side. All it does is change the distribution
of the graph outward from the left side.

The left side of the histogram is only an artifact of conversion, and the arbitrary curve used on the X axis. The top stops are usually made to look like each stop takes the same percentage of the entire histogram, but the left side suddenly turns linear, creating a left edge. If the spacing used on the right side were used on the left, the left side of the histogram would never reach black; it would go on to infinity.

Talking about the left edge of a histogram is usually gibberish. It is SNR which determines the quality of RAW shadows; not histogram positions.

I agree with all of the above.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

"Wilba" wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the left, so that’s a waste of time.

Yes for the histogram, but it is not a waste of time.

Increasing the exposure adds signal, but the noise stays the same. In other words, if you take a shot of an
object that is all grey, with nothing approaching
"white" at all in the entire scene, you could

1) Expose to produce an histogram that matches
the scene, showing all values to be in the
middle of the graph. This will produce an
accurately exposed JPEG too.

or,

2) Expose to produce an histogram with the data
pushed so far to the right that it is almost,
but not quite, clipping. The JPEG produce
will be "overexposed", and instead of grey
the scene will be white.

But we want an image made from the camera raw data, not
the JPEG. And note that with either of the above
methods the "noise" in the data will be the same. The Signal to Noise Ratio (SNR) for method #2 will be higher because the signal is higher.

The final image is made using the RAW converter, or an
image editor like Photoshop after conversion, to reduce
the whites down to grey. And the same process will
*equally* reduce the noise. Thus the noise in the final image will be *lower* with method 2 than with method 1.

Reducing the amount of noise in the final product is
probably *not* a waste of time.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Paul Furman

Oct 8, 2009

Floyd L. Davidson wrote:

Paul Furman wrote:

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

But regardless of that, the cited URL above from
luminous-landscape is *not* full of good stuff. They
miss the point entirely, and provide nothing that is
actually useful! All that changing in-camera contrast
does is compress/uncompress the histograms idea of
middle gray. It does not change where the highlights
fall, and thus does not change what you would set for
the exposure. (Does anyone ever look at the shape of an in-camera histogram and make adjustments as a result?
It’s a meaningless excercise, which will not change the
camera raw data. The shape of a post processing
histogram is very useful, but not an in-camera
histogram.)

What you say is wrong for the Canon 30D. The histogram does not change the raw data stored by the camera. But the camera setting DOES change the camera displayed histogram. IF you set the camera "comtrast" setting high, the highlights in the histogram get pushed way up and are indeed useless for setting exposure. Ii you set it low, at -3 or -4, the histogram displayed by the camera agrees quite nicely with how close you are getting to clipping.

The brightest part will still show at *exactly* the
same
place.

Maybe for contrast (though I doubt it) but WB makes a big difference. I just tested at 25K & 100K, the highlights are completely different. I’m looking at split RGB histograms btw.

That is exactly the point I *am* making. WB changes the histogram in a useful way. The Luminous-Landscape
article did not talk about WB at all. They discussed
changing the camera’s setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue.

And if you doubt that the contrast setting will not change the histogram as stated, *try* *it*. I gave an step by
step description of a very easy way to show exactly what does and does not happen. Why argue from supposition when you could actually learn something about photography…

I am interested in learning. I tried fiddling with the camera contrast settings to compare histograms and the difference was very minor, at least for the conditions I tried just now. I was thinking of post-processing where increasing contrast blows highlights & blocks shadows. Maybe not the very final edge of 100% saturation but contrast adjustments can make a big difference in what appears to be blown or blocked. What you are describing sounds more like a gamma adjustment than contrast where only the middle part shifts.

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman

Oct 8, 2009

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can be a problem in dark areas…

The only cameras I know of with even a hint of RAW posterization are the Pentax K10D, which would profit from 13 bits instead of 12 at ISO 100 (not for 200 or higher), the Sony A900 also with a need for 13 bits at base, and the D3X when in 12-bit mode. These are only on the fringe of posterizing.

raising shadows in post for the deepest shadows, and in skies where the color pallet is very limited. Doesn’t the noise level follow this same principle? Or is there an unrelated reason for the noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most likely caused by the math used in the converter, and nothing else. Of course, JPEG compression does some posterization of its own, especially if you use too much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS. http://www.luminous-landscape.com/tutorials/expose-right.sht ml

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Paul Furman

Oct 8, 2009

DRS wrote:

"Floyd L. Davidson" wrote in message

[…]

The point is still the same, contrast settings do *not*
affect the exposure.

Since nobody has said it does why don’t you slow down and pay attention to what is being said?

What is being said is that where manufacturers draw the histogram settings from the compressed JPEG instead of the Raw image, lowering the contrast setting will render the histogram more accurately (closer to the Raw). The claim is that this more accurate histogram *subsequently* enables the photographer to make more accurate adjustments to the exposure.
Check out the images under the heading "Contrast adjustment" on this page: http://www.dpreview.com/reviews/CanonEOS30D/page13.asp. The luminosity histogram expands left and right as you increase the contrast. If you were to judge by the +4 histogram you would think the image was clipping both highlights and shadows but this is not the case.

If the histogram at -4 is in fact more accurate than the histogram at 0 (the Canon default) then the photographer in fact has greater room for exposure compensation to the right than the histogram at contrast setting 0 indicates. For those wishing to compensate to the right this is useful information. What the photographer *subsequently* chooses to do to the exposure is another discussion entirely.

What about saturation? Reducing saturation seems to give more detail to the edges also.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Clues

Oct 8, 2009

On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy wrote:

Exposure to the right is usually given as advice for RAW shooting. The RAW data usually clips well above the level where a JPEG would clip it,

Very true, for all those cameras that intentionally do a poor job at the RAW to JPG conversion. This is why RAW became so popular. DSLRs are inherently poor at this process. In fact it’s the very reason that having access to the RAW data became so popular. Far too many DSLR owners wanted to repair in their resulting images what the DSLR’s firmware programmers failed to do correctly in the first place. Companies then realized that they could turn this into an asset. Not only sell a camera that didn’t work quite right, bundled with a kit-lens that wouldn’t provide images any better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to make their $500 DSLR functional, but now also sell them expensive editing software to fix what their cameras weren’t doing properly to provide a useful image right out of the box.

A popular business model for the last couple of decades. Not unlike how microsoft popularized this practice. They released Win95 in alpha phase (I was a pre-beta-tester and read the in-house memos back then). M$ was worried that they’d get sued worldwide for false-advertising if it wasn’t released on the promised date. In fact they were already behind several deadlines and lawyers were starting to circle, ready to get their piece of the M$ castle. M$ decided to go ahead and ship the alpha-phase Win95 anyway. What buyer would ever know. They then also charged (on a per-call basis) their customers who bought this unfinished software for the tech-support needed to get it running somewhat. A very effective means to increase the profitability of an incomplete or improperly functioning product. (This is why you should never buy any windows platform until after the second or third service-pack is released. Let all the others happily and foolishly pay for the privilege to be microsoft’s beta-tester grunts. When the reverse should be true. M$ should pay everyone to try out the first few issues of their latest versions. If they’re lucky, and they pay all their beta-testers enough for all the time and work involved, we might even tell M$ what is wrong.)

Sell them a DSLR that should work well and produce a useful image, but doesn’t. Then provide a $5,000-$10,000 lens and $200 software that they’ll need to get it working right. It’s just the M$ marketing strategy applied to cameras, nothing more. Your valuable time that you spend in editing all your RAW images for this privilege is merely a courtesy feature and should go unmentioned, lest people become even more angry over how they’ve been cunningly turned into more CEOs’ saps.

There are many cameras now on the market where you will find little need for RAW. Take the RAW data and try to get it to look better than the JPG from the camera and you’ll be hard pressed to better it. They manage to do the process right the first time with no need for time-consuming RAW editing intervention, other than setting white-balance and exposure properly while shooting, as any decent photographer will and should.

Yes, they could easily provide the JPG images in the 16-bit HD-Photo format (nearly all good editors fully support it) with compression ratio saving options (as all editors do), for those of you that understand the need for the extra data when trying to recover from your snapshooters’ mistakes and accidents. But then how could they sell the required RAW editing software to you too? Not going to happen if they can find a simple way to make you pay more of your money and waste even more of your valuable time.

Enjoy your crippled cameras. You got exactly what you were willing to pay for.

DRS

Oct 8, 2009

"Paul Furman" wrote in message

DRS wrote:

[…]

If the histogram at -4 is in fact more accurate than the histogram at 0 (the Canon default) then the photographer in fact has greater room for exposure compensation to the right than the histogram at contrast setting 0 indicates. For those wishing to compensate to the right this is useful information. What the photographer *subsequently* chooses to do to the exposure is another discussion entirely.

What about saturation? Reducing saturation seems to give more detail to the edges also.

That is possible but not something for which I have evidence. My concern here was to short-circuit this increasingly hysterical subthread by demonstrating that Floyd has been tilting at windmills. Everything Doug McDonald has said about the effect on the histogram of changing the contrast setting on the 30D is borne out by the images on the page to which I linked. Since all the major DSLR manufacturers, to the best of my knowledge, derive histograms from the JPEGs then what he has described would be universally applicable.

floyd

Oct 8, 2009

"DRS" wrote:

"Paul Furman" wrote in message

DRS wrote:

[…]

If the histogram at -4 is in fact more accurate than the histogram at 0 (the Canon default) then the photographer in fact has greater room for exposure compensation to the right than the histogram at contrast setting 0 indicates. For those wishing to compensate to the right this is useful information. What the photographer *subsequently* chooses to do to the exposure is another discussion entirely.

What about saturation? Reducing saturation seems to give more detail to the edges also.

That is possible but not something for which I have evidence. My concern here was to short-circuit this increasingly hysterical subthread by demonstrating that Floyd has been tilting at windmills. Everything Doug McDonald has said about the effect on the histogram of changing the contrast setting on the 30D is borne out by the images on the page to which I linked. Since all the major DSLR manufacturers, to the best of my knowledge, derive histograms from the JPEGs then what he has described would be universally applicable.

The web page you cited has absolutely *nothing* on it
that supports what you or McDonald have said. It talks
only about the effect of changing contrast settings on
the resulting JPEG image, not on the exposure or how it
affects camera raw data.

The histogram images show that *no* change in exposure
is demonstrated, and that *logically* it is not possible to improve the accuracy of the histogram. (Indeed, the
histograms shown are apparently purposely styled, with a white foreground against a *grey* background and with a
grey scale at the bottom so that the lower right corner
has a white border against the white foreground. They
have made it impossible to see where the right edge of
the data is!)

What it does show is that the peaks in the graph get
moved around, and if you *mistakenly* believe that where the peak is at is related to exposure, you will
mistakenly think that contrast has somehow helped.

The problem with saying that contrast adjustments make
it more obvious where the right edge of the graph is at
is that different setting help or hinder with different
types of scenes. For one scene you might well be right
that it is easier to see with low contrast, but just the same for the next scene you shoot it could be high
contrast that would help. It is *not* inherently better for all purposes when set to low contrast!

Showing that it helps to see the edge in one condition
without being aware that the condition is a special
case, leads to a logically invalid conclusion.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 8, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

That is possible but not something for which I have evidence. My concern here was to short-circuit this increasingly hysterical subthread by demonstrating that Floyd has been tilting at windmills. Everything Doug McDonald has said about the effect on the histogram of changing the contrast setting on the 30D is borne out by the images on the page to which I linked. Since all the major DSLR manufacturers, to the best of my knowledge, derive histograms from the JPEGs then what he has described would be universally applicable.

The web page you cited has absolutely *nothing* on it
that supports what you or McDonald have said. It talks
only about the effect of changing contrast settings on
the resulting JPEG image, not on the exposure or how it
affects camera raw data.

That is because they are two different things which nobody has conflated but you. The images on that site show exactly what Doug McDonald claimed and nothing more. Of course they show nothing on the effect on exposure or on Raw data but that was never the claim except in your mind. You have created a straw man.

The histogram images show that *no* change in exposure
is demonstrated, and that *logically* it is not possible to improve the accuracy of the histogram.

It is possible to improve the accuracy of the histogram relative to the Raw data and the fact that you cannot see it when it is right before your eyes is your problem, not ours. Those images show 5 different histograms where the only variable is the contrast setting. Since the exposure has not changed then only one of the histograms can be the most accurate relative to the Raw image. It happens to be the -4 setting.

[…]

What it does show is that the peaks in the graph get
moved around, and if you *mistakenly* believe that where the peak is at is related to exposure, you will
mistakenly think that contrast has somehow helped.

Straw man. All five histograms have different right-edges, indicating different possibilities for exposure compensation before clipping occurs. One of the 5 most accurately indicates the true feasible extent of ETTR, and that one is the -4 histogram. That is all that has been claimed.

The problem with saying that contrast adjustments make
it more obvious where the right edge of the graph is at
is that different setting help or hinder with different
types of scenes. For one scene you might well be right
that it is easier to see with low contrast, but just the same for the next scene you shoot it could be high
contrast that would help. It is *not* inherently better for all purposes when set to low contrast!

The question of when ETTR is suitable is a different question again., and is not something I addressed.

Showing that it helps to see the edge in one condition
without being aware that the condition is a special
case, leads to a logically invalid conclusion.

You are really not in any position to lecture on logic.

floyd

Oct 8, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

That is possible but not something for which I have evidence. My concern here was to short-circuit this increasingly hysterical subthread by demonstrating that Floyd has been tilting at windmills. Everything Doug McDonald has said about the effect on the histogram of changing the contrast setting on the 30D is borne out by the images on the page to which I linked. Since all the major DSLR manufacturers, to the best of my knowledge, derive histograms from the JPEGs then what he has described would be universally applicable.

The web page you cited has absolutely *nothing* on it
that supports what you or McDonald have said. It talks
only about the effect of changing contrast settings on
the resulting JPEG image, not on the exposure or how it
affects camera raw data.

That is because they are two different things which nobody has conflated but you. The images on that site show exactly what Doug McDonald claimed and nothing more. Of course they show nothing on the effect on exposure or on Raw data but that was never the claim except in your mind. You have created a straw man.

It may show what Doug is talking about, but it shows
that it has nothing to do with correct exposure, which
*is* the point of this discussion.

You continue to say that effect on exposure in not
significant, but the *fact* is that is the *only* thing
that would be significant. You *cannot* get more
accurate exposure without making the histogram more
accurate. Contrast settings change the shape of the
graph between the right most edge and the the left edge
*but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.

You continue to say that low contrast makes it easier to see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

The histogram images show that *no* change in exposure
is demonstrated, and that *logically* it is not possible to improve the accuracy of the histogram.

It is possible to improve the accuracy of the histogram relative to the Raw data and the fact that you cannot see it when it is right before your eyes is your problem, not ours. Those images show 5 different histograms where the only variable is the contrast setting. Since the exposure has not changed then only one of the histograms can be the most accurate relative to the Raw image. It happens to be the -4 setting.

All five show *exactly* the same exposure. I assume you are looking at the large peaks of the graph as they move more towards the right edge. That of course is *not* a
measure of exposure.

If the graphs were designed to show the effect they
would also have to show histograms for some lower
exposure and at some higher exposure, to demonstrate
what one has to adjust for.

[…]

What it does show is that the peaks in the graph get
moved around, and if you *mistakenly* believe that where the peak is at is related to exposure, you will
mistakenly think that contrast has somehow helped.

Straw man. All five histograms have different right-edges, indicating different possibilities for exposure compensation before clipping occurs. One of the 5 most accurately indicates the true feasible extent of ETTR, and that one is the -4 histogram. That is all that has been claimed.

They all have exactly the same right edge, to the degree that it can be determined (which is exceedingly
difficult because the images were designed purposely to
de-emphasize that and to emphasize the changes that
contrast actually does cause. That of course is
perfectly reasonable because that is the topic they are
discussing, and is the reason they do not mention
exposure at all.

The problem with saying that contrast adjustments make
it more obvious where the right edge of the graph is at
is that different setting help or hinder with different
types of scenes. For one scene you might well be right
that it is easier to see with low contrast, but just the same for the next scene you shoot it could be high
contrast that would help. It is *not* inherently better for all purposes when set to low contrast!

The question of when ETTR is suitable is a different question again., and is not something I addressed.

The above has nothing at all to do with suitability of
ETTR, it is not something I’ve addressed either. Why
are you?

Showing that it helps to see the edge in one condition
without being aware that the condition is a special
case, leads to a logically invalid conclusion.

You are really not in any position to lecture on logic.

Other than I use it, and you don’t? Seems like a good
position…

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Mike Russell

Oct 8, 2009

On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:

[re film’s "expose for shadows", digital’s "expose for the highlights"]

Actually, since film is a negative, the two are in fact
actually the same. Expose for the brightest range of the *recording* *mechanism*.

That just happens to be the dark areas of a scene with
film (where the negative is clear) and the bright areas
of a scene with an electronic sensor (the highest
voltage output).

No – both refer to areas of the scene. The full rule of thumb for film is "Expose for the shadows. Develop for the highlights". Exposing for the shadows establishes the area of minimum negative density, and development has a much greater effect on the highlights than the shadows.

For digital, exposing for the highlights amounts to playing chicken with the brightest significant information in the image, by choosing an exposure and ISO that puts the brightest significant subject material as close as possible to the max sensor value, without actually losing information.

Your other points are technically true, but belie the fact that film’s Achilles heel is loss of subject shadow detail, while digital’s is loss of subject highlight detail.
<snip>
—
Mike Russell – http://www.curvemeister.com

DRS

Oct 8, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

That is because they are two different things which nobody has conflated but you. The images on that site show exactly what Doug McDonald claimed and nothing more. Of course they show nothing on the effect on exposure or on Raw data but that was never the claim except in your mind. You have created a straw man.

It may show what Doug is talking about, but it shows
that it has nothing to do with correct exposure, which
*is* the point of this discussion.

More accurate histograms are part of the information a photographer needs in order to make good decisions about what *subsequently* to do about the exposure settings.

You continue to say that effect on exposure in not
significant, but the *fact* is that is the *only* thing
that would be significant.

Nobody ever said any such thing. Stop making shit up.

You *cannot* get more
accurate exposure without making the histogram more
accurate.

Of course. That is what has been said all along.

Contrast settings change the shape of the
graph between the right most edge and the the left edge
*but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.

Yes, they do. Everybody sees it except you. Increase the contrast setting and the histogram expands left and right. Decrease contrast and the edges shift inwards especially on the right edge. The change in the location of the right edge between -4 and +4 stands out like dog’s balls.

[…]

You continue to say that low contrast makes it easier to see where the edge is,

No, what has been said is that changing the contrast setting changes the location of the right edge, which in turn renders the histogram more or less accurate. Low contrast shifts the right edge to the left and the claim is that this more accurately resembles the Raw data.

[…]

It is possible to improve the accuracy of the histogram relative to the Raw data and the fact that you cannot see it when it is right before your eyes is your problem, not ours. Those images show 5 different histograms where the only variable is the contrast setting. Since the exposure has not changed then only one of the histograms can be the most accurate relative to the Raw image. It happens to be the -4 setting.

All five show *exactly* the same exposure.

That is not in dispute. If you payed attention you’d have noticed that in that very paragraph I said, "Since the exposure has not changed…" The fact that the exposure is the same is necessary to the point being made, which is that changing one and only one variable, the contrast setting, changes the accuracy of the histogram upon which decisions about exposure are *subsequently* made. I keep putting the word "subsequently" in bold because you just don’t get it. Decisions about exposure come after the point under discussion.

[…]

They all have exactly the same right edge, to the degree that it can be determined (which is exceedingly

No, they don’t. Blind Freddy can see the right-edges shift by at least 1 stop from -4 to +4, and probably more. And before you jump on your exposure hobby-horse don’t. That has nothing to do with the actual exposure settings. It is simply an indication of the real amount of exposure compensation that is possible before clipping occurs.

[…]

You are really not in any position to lecture on logic.

Other than I use it, and you don’t? Seems like a good
position…

The proof is in the pudding is in the eating.

floyd

Oct 8, 2009

Mike Russell wrote:

On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:
[re film’s "expose for shadows", digital’s "expose for the highlights"]

Actually, since film is a negative, the two are in fact
actually the same. Expose for the brightest range of the *recording* *mechanism*.

That just happens to be the dark areas of a scene with
film (where the negative is clear) and the bright areas
of a scene with an electronic sensor (the highest
voltage output).

No – both refer to areas of the scene. The full rule of thumb for film is "Expose for the shadows. Develop for the highlights". Exposing for the shadows establishes the area of minimum negative density, and development has a much greater effect on the highlights than the shadows.
For digital, exposing for the highlights amounts to playing chicken with the brightest significant information in the image, by choosing an exposure and ISO that puts the brightest significant subject material as close as possible to the max sensor value, without actually losing information.
Your other points are technically true, but belie the fact that film’s Achilles heel is loss of subject shadow detail, while digital’s is loss of subject highlight detail.
<snip>

Interesting way to say, "No, you are right."

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

Contrast settings change the shape of the
graph between the right most edge and the the left edge
*but* *do* *not* *change* *the* *location* *of* *the* *right* *edge*.

Yes, they do. Everybody sees it except you. Increase the contrast setting and the histogram expands left and right. Decrease contrast and the edges shift inwards especially on the right edge. The change in the location of the right edge between -4 and +4 stands out like dog’s balls.

….

It is possible to improve the accuracy of the histogram relative to the Raw data and the fact that you cannot see it when it is right before your eyes is your problem, not ours. Those images show 5 different histograms where the only variable is the contrast setting. Since the exposure has not changed then only one of the histograms can be the most accurate relative to the Raw image. It happens to be the -4 setting.

All five show *exactly* the same exposure.

That is not in dispute. If you payed attention you’d have noticed that in that very paragraph I said, "Since the exposure has not changed…" The fact that the exposure is the same is necessary to the point being made, which is that changing one and only one variable, the contrast setting, changes the accuracy of the histogram upon which decisions about exposure are *subsequently* made.

You can’t have it both ways. First you say that the
contrast setting moves the histogram’s indication of
exposure, and now you say it does not.

All five of those histograms show *exactly* the same
exposure, even though they have 5 different contrast
settings.

If that is the desired exposure, not one of those
histograms would suggest that the camera’s exposure
should be changed to be more accurate.

They all have exactly the same right edge, to the degree that it can be determined (which is exceedingly

No, they don’t. Blind Freddy can see the right-edges shift by at least 1 stop from -4 to +4, and probably more.

You apparently are looking at that huge peak value to
the left of the right edge, as it is the only thing that moves by "at least 1 stop". But that peak has *nothing* to do with setting correct exposure. See the little
itty bitty value down in the lower right hand corner?

That is the value of significance. That is the "right edge".

You are really not in any position to lecture on logic.

Other than I use it, and you don’t? Seems like a good
position…

The proof is in the pudding is in the eating.

Cute. I’ll settle for being logical.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 8, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

That is not in dispute. If you payed attention you’d have noticed that in that very paragraph I said, "Since the exposure has not changed…" The fact that the exposure is the same is necessary to the point being made, which is that changing one and only one variable, the contrast setting, changes the accuracy of the histogram upon which decisions about exposure are *subsequently* made.

You can’t have it both ways. First you say that the
contrast setting moves the histogram’s indication of
exposure, and now you say it does not.

I have always said it changes the indication of exposure. It is you who made the false claim that I and others were saying it had anything to do with changing the actual exposure, which we have repeatedly denied.

All five of those histograms show *exactly* the same
exposure, even though they have 5 different contrast
settings.

And because of the different contrast settings the 5 histograms show the exposure differently. The exposure hasn’t changed but the accuracy of its representation has. Which is all that has been claimed.

If that is the desired exposure, not one of those
histograms would suggest that the camera’s exposure
should be changed to be more accurate.

None of the 5 histograms indicate overexposure. What they do indicate, to different degrees of accuracy, is the room for exposure compensation. Only 1 can be the most accurate and it is the -4 histogram.

[…]

No, they don’t. Blind Freddy can see the right-edges shift by at least 1 stop from -4 to +4, and probably more.

You apparently are looking at that huge peak value to
the left of the right edge, as it is the only thing that moves by "at least 1 stop". But that peak has *nothing* to do with setting correct exposure. See the little
itty bitty value down in the lower right hand corner?

That is the value of significance. That is the "right edge".

In this instance that indicates specular highlights, which as has been noted by several people, may be blown without spoiling the image. That is a choice by the photographer.

[…]

The proof is in the pudding is in the eating.

Cute. I’ll settle for being logical.

Good. I hope to see it soon.

floyd

Oct 8, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

That is not in dispute. If you payed attention you’d have noticed that in that very paragraph I said, "Since the exposure has not changed…" The fact that the exposure is the same is necessary to the point being made, which is that changing one and only one variable, the contrast setting, changes the accuracy of the histogram upon which decisions about exposure are *subsequently* made.

You can’t have it both ways. First you say that the
contrast setting moves the histogram’s indication of
exposure, and now you say it does not.

I have always said it changes the indication of exposure. It is you who made the false claim that I and others were saying it had anything to do with changing the actual exposure, which we have repeatedly denied.

All five of those histograms show *exactly* the same
exposure, even though they have 5 different contrast
settings.

*All* *five* *show* *the* *exact* *same* *exposure*.

Not one of them shows any 1 f/stop difference as you
claim.

The only thing that moves 1 f/stop are the tall peaks in the graph that have *nothing* to do with exposure. It
is well to the left of the right edge, and it is that
right edge that indicates exposure.

And because of the different contrast settings the 5 histograms show the exposure differently. The exposure hasn’t changed but the accuracy of its representation has. Which is all that has been claimed.

They *don’t* show the *exposure* differently.

If that is the desired exposure, not one of those
histograms would suggest that the camera’s exposure
should be changed to be more accurate.

None of the 5 histograms indicate overexposure. What they do indicate, to different degrees of accuracy, is the room for exposure compensation. Only 1 can be the most accurate and it is the -4 histogram.

All of them indicate there is no room for any
"compensation". Increasing the camera exposure will result in clipping, and each of those histograms shows
that.

Oddly enough, the +4 histogram shows it the best!

No, they don’t. Blind Freddy can see the right-edges shift by at least 1 stop from -4 to +4, and probably more.

You apparently are looking at that huge peak value to
the left of the right edge, as it is the only thing that moves by "at least 1 stop". But that peak has *nothing* to do with setting correct exposure. See the little
itty bitty value down in the lower right hand corner?

That is the value of significance. That is the "right edge".

In this instance that indicates specular highlights, which as has been noted by several people, may be blown without spoiling the image. That is a choice by the photographer.

The tall peaks are *not* a "specular highlights", and one look at the image should demonstrate that there are
no light sources or reflections in the image. Those
peaks are probably the whiter parts of the background,
but might be from one or more of the crayons too. It
isn’t possible to determine from looking at the
histograms just where the actual values are that make up either those peaks or the right edge of the histogram.
It does appear that the whitest part of the watch face,
around the 12 and 6, are probably where the right edge of the histogram values are from.

Note that only in the +4 histogram are the values at the right edge more than maybe 2 pixels high on that graph.
They are very hard to see because of the white portion
of the gray scale below the graph and the lack of
contrast with the gray background.

The proof is in the pudding is in the eating.

Cute. I’ll settle for being logical.

Good. I hope to see it soon.

With a bit of logic you’d have seen it already.

You know, logically if what you said made sense the
article would have discussed it in some way, but it does not even hint at it. If changing the contrast displayed a more accurate *exposure* (right edge location), why
didn’t they point to it?

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

Paul Furman wrote:

Floyd L. Davidson wrote:

That is exactly the point I *am* making. WB changes
the
histogram in a useful way. The Luminous-Landscape
article did not talk about WB at all. They discussed
changing the camera’s setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue.
And if you doubt that the contrast setting will not
change
the histogram as stated, *try* *it*. I gave an step by
step description of a very easy way to show exactly what does and does not happen. Why argue from supposition when you could actually learn something about photography…

I am interested in learning. I tried fiddling with the camera contrast settings to compare histograms and the difference was very minor, at least for the conditions I tried just now. I was thinking of post-processing where increasing contrast blows highlights & blocks shadows. Maybe not the very final edge of 100% saturation but contrast adjustments can make a big difference in what appears to be blown or blocked. What you are describing sounds more like a gamma adjustment than contrast where only the middle part shifts.

"Gamma is equivalent to contrast. This can be observed in traditional film curves, which are displayed on
logarithmic scales (typically, density (log10(absorbed
light) vs. log10(exposure)). Gamma is the average
slope of this curve (excluding the "toe" and
"shoulder" regions near the ends of the curve), i.e., the contrast."
http://www.imatest.com/docs/glossary.html
(The above is a web page owned by Norman Koren.)

"Gamma — A way of representing the contrast of an
image, shown as the slope of a curve showing tones
from white to black."
http://www.hp.com/united-states/consumer/digital_photography /articles/scanner_glossary.html

That might help make things clearer as to why changing
contrast does not make the histogram any more or less
accurate for exposure.

When the histogram indicates precisely the correct
exposure, changing the gamma (contrast) moves the curve
between black and maximum white values, but it doesn’t
change the value of either. Note too that it might
spread the histogram out from the center (if the gamma
curve is moved by picking a point at its center), or it
might move towards ether the right or the left (if the
gamma curve is moved from point closer to the ends
instead of at the center).

In any case, it changes the contrast but if there are
image values at the maximum white value they will not be moved.

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

I don’t use those programs so I can only provide general instructions about how that is typically done. I’ll
leave it to someone who can be more specific.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

Paul Furman wrote:

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can
be a problem in dark areas…

The only cameras I know of with even a hint of RAW
posterization are the Pentax K10D, which would profit
from 13 bits instead of 12 at ISO 100 (not for 200 or
higher), the Sony A900 also with a need for 13 bits at
base, and the D3X when in 12-bit mode. These are only
on the fringe of posterizing.

raising shadows in post for the deepest shadows, and
in skies where the color pallet is very
limited. Doesn’t the noise level follow this same
principle? Or is there an unrelated reason for the
noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most
likely caused by the math used in the converter, and
nothing else. Of course, JPEG compression does some
posterization of its own, especially if you use too
much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS. http://www.luminous-landscape.com/tutorials/expose-right.sht ml

That is an *excellent* article. It also has a link to
another article, titled "Understanding Histograms", which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

http://www.luminous-landscape.com/tutorials/understanding-se ries/understanding-histograms.shtml

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 8, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

I have always said it changes the indication of exposure. It is you who made the false claim that I and others were saying it had anything to do with changing the actual exposure, which we have repeatedly denied.

*All* *five* *show* *the* *exact* *same* *exposure*.

Yes, how many times do I have to tell you that before you get it?

Not one of them shows any 1 f/stop difference as you
claim.

Yes, they do, in terms of *accuracy*.

The only thing that moves 1 f/stop are the tall peaks in the graph that have *nothing* to do with exposure. It
is well to the left of the right edge, and it is that
right edge that indicates exposure.

The right edge moves.

And because of the different contrast settings the 5 histograms show the exposure differently. The exposure hasn’t changed but the accuracy of its representation has. Which is all that has been claimed.

They *don’t* show the *exposure* differently.

Yes, they do. Everybody can see it except you.

None of the 5 histograms indicate overexposure. What they do indicate, to different degrees of accuracy, is the room for exposure compensation. Only 1 can be the most accurate and it is the -4 histogram.

All of them indicate there is no room for any
"compensation". Increasing the camera exposure will result in clipping, and each of those histograms shows
that.

No, they don’t. Try looking at what is there.

[…]

In this instance that indicates specular highlights, which as has been noted by several people, may be blown without spoiling the image. That is a choice by the photographer.

The tall peaks are *not* a "specular highlights", and

I didn’t say they were. Do you ever pay attention? You can’t even follow when I’m addressing your argument!

[…]

You know, logically if what you said made sense the
article would have discussed it in some way, but it does not even hint at it. If changing the contrast displayed a more accurate *exposure* (right edge location), why
didn’t they point to it?

"What does all this mean? In order to display the full dynamic range of your camera in the histogram displayed on the back, you must set the contrast to minimum. You now can see the same dynamic range in the histogram on the camera as you will see it in your RAW processor on your computer."

Porte Rouge

Oct 8, 2009

On Oct 8, 6:22 am, (Floyd L. Davidson) wrote:

Paul Furman wrote:

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can
be a problem in dark areas…

The only cameras I know of with even a hint of RAW
posterization are the Pentax K10D, which would profit
from 13 bits instead of 12 at ISO 100 (not for 200 or
higher), the Sony A900 also with a need for 13 bits at
base, and the D3X when in 12-bit mode.  These are only
on the fringe of posterizing.

raising shadows in post for the deepest shadows, and
in skies where the color pallet is very
limited. Doesn’t the noise level follow this same
principle? Or is there an unrelated reason for the
noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most
likely caused by the math used in the converter, and
nothing else.  Of course, JPEG compression does some
posterization of its own, especially if you use too
much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS.http://www.luminous-landscape.com/tutorials/expose-right. shtml

That is an *excellent* article.  It also has a link to
another article, titled "Understanding Histograms", which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

Porte Rouge

Oct 8, 2009

On Oct 7, 8:21 pm, "Wilba" wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the left, so that’s a waste of time. To avoid having the deep colours washed out, you need to make use of the full tonal range available in the image. If you have done a good job of exposing to the right, your highlights will be pretty much where they need to be. So then all you need to do is raise the black point (e.g. using the Levels dialog in Photoshop), so that the dark tones in the scene end up as dark tones in the image. If you are using the Levels dialog in Photoshop, while you drag the black (or white) point slider, press the Alt key to see which pixels are clipped (or blown).
(The following relates to my experience with a Canon 450D. YMMV.)

Aha!

There are two parts to exposing to the right – levels in the image and saturation of photosites. Whether you are shooting JPEG or raw, the camera’s histogram display shows you the levels in a JPEG produced from the raw data, so the shape of the histogram curve depends on your settings for sharpness, contrast, saturation, colour tone, etc.

If you are shooting JPEG, all you can do is avoid piling up the histogram on the right, which prevents gross areas of blown highlights in the image.
If you are shooting raw, you can overexpose (beyond the point at which the histogram curve touches the right boundary), by about two steps and still produce an image from the raw without blown highlights. IOW, the headroom between blown highlights in the JPEG and saturation of the photosites is about two steps (in my experience, with the JPEG settings I use).
So if you are bracketing for the best possible exposure, go at least two steps over what the histogram tells you is "correct". The maximum possible dynamic range occurs at the point where photosites in the highlights begin to saturate.

What do you mean by steps? Do you mean stops, or steps on the aperture or shutter dials?

In everyday raw shooting, you can be quite relaxed about having a small spike on the right of the histogram – that’s actually a good thing.

Doug McDonald

Oct 8, 2009

Floyd L. Davidson wrote:

I have performed tests on my Canon 30D camera to see
what happens if I expose less. I exposed 1/3 and 2/3
stops less than before.

At 2/3 stop less than before yes, even at contrast setting zero, I do see a teensy bit of space between the top of the red histogram and the top of the display. This means that if I’m willing to lose 2/3 stop of unclipped data at the bright end, Floyd is "effectively" right.

But if I want that extra 2/3 stop, I’m still correct.

I should add that my method works — I use -4 in the camera, use the histogram, and find my raw images are very nicely exposed, no clipping (except as desired for specular highlights) and the data right up to the clipping level.

Doug McDonald

Doug McDonald

Oct 8, 2009

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.

You continue to say that low contrast makes it easier to see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

Doug McDonald

Paul Furman

Oct 8, 2009

Floyd L. Davidson wrote:

Paul Furman wrote:

Floyd L. Davidson wrote:

That is exactly the point I *am* making. WB changes
the histogram in a useful way. The Luminous-Landscape
article did not talk about WB at all. They discussed
changing the camera’s setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue. And if you doubt that the contrast setting will not change the histogram as stated, *try* *it*. I gave an step by step description of a very easy way to show exactly what does and does not happen. Why argue from supposition when you could actually learn something about photography…

I am interested in learning. I tried fiddling with the camera contrast settings to compare histograms and the difference was very minor, at least for the conditions I tried just now.

A second try showed a significant difference.

I was thinking of
post-processing where increasing contrast blows highlights & blocks shadows. Maybe not the very final edge of 100% saturation but contrast adjustments can make a big difference in what appears to be blown or blocked. What you are describing sounds more like a gamma adjustment than contrast where only the middle part shifts.

Scratch that comment, they both have an effect.

"Gamma is equivalent to contrast.

I dunno, maybe your linked definers are thinking of a different context. Common sense and experience tell me gamma is adjusting the middle-value, more like brightness, without changing the the ends. Contrast adjustments tend to hold the mid-point and use an s curve to raise highlights & lower shadows or the inverse. A gamma adjustment curve is a fairly simple bowed shape, not an s shape. Sure a gamma adjustment has an effect on contrast but that’s a side effect, not the goal. Gamma adjustments boost contrast in either the highlights or shadows, not both.

This can be observed
in traditional film curves, which are displayed on
logarithmic scales (typically, density (log10(absorbed
light) vs. log10(exposure)). Gamma is the average
slope of this curve (excluding the "toe" and
"shoulder" regions near the ends of the curve), i.e., the contrast."
http://www.imatest.com/docs/glossary.html
(The above is a web page owned by Norman Koren.)

"Gamma — A way of representing the contrast of an
image, shown as the slope of a curve showing tones
from white to black."
http://www.hp.com/united-states/consumer/digital_photography /articles/scanner_glossary.html
That might help make things clearer as to why changing
contrast does not make the histogram any more or less
accurate for exposure.

When the histogram indicates precisely the correct
exposure, changing the gamma (contrast) moves the curve
between black and maximum white values, but it doesn’t
change the value of either. Note too that it might
spread the histogram out from the center (if the gamma
curve is moved by picking a point at its center), or it
might move towards ether the right or the left (if the
gamma curve is moved from point closer to the ends
instead of at the center).

In any case, it changes the contrast but if there are
image values at the maximum white value they will not be moved.

The maximum white value may be already off the edge so you are talking about part of the middle of the curve, which is effected, showing more detail with low contrast.

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

I don’t use those programs so I can only provide general instructions about how that is typically done. I’ll
leave it to someone who can be more specific.

Understanding this would help in simulating exposure changes in an editor – to better understand when shooting & interpreting the histogram.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

floyd

Oct 8, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

I have always said it changes the indication of exposure. It is you who made the false claim that I and others were saying it had anything to do with changing the actual exposure, which we have repeatedly denied.

*All* *five* *show* *the* *exact* *same* *exposure*.

Yes, how many times do I have to tell you that before you get it?

Not one of them shows any 1 f/stop difference as you
claim.

Yes, they do, in terms of *accuracy*.

You simply do not know how to read a histogram, and until you learn there is little point in talking to you on any topic that requires it.

The only thing that moves 1 f/stop are the tall peaks in the graph that have *nothing* to do with exposure. It
is well to the left of the right edge, and it is that
right edge that indicates exposure.

The right edge moves.

It doesn’t. You are *not* looking at the right edge, you are looking at a peak that is left of the edge. The peak moves, the edge does not.

And because of the different contrast settings the 5 histograms show the exposure differently. The exposure hasn’t changed but the accuracy of its representation has. Which is all that has been claimed.

They *don’t* show the *exposure* differently.

Yes, they do. Everybody can see it except you.

Everyone who knows how to read a histogram can see the same thing that I do.

None of the 5 histograms indicate overexposure. What they do indicate, to different degrees of accuracy, is the room for exposure compensation. Only 1 can be the most accurate and it is the -4 histogram.

All of them indicate there is no room for any
"compensation". Increasing the camera exposure will result in clipping, and each of those histograms shows
that.

No, they don’t. Try looking at what is there.

[…]

In this instance that indicates specular highlights, which as has been noted by several people, may be blown without spoiling the image. That is a choice by the photographer.

The tall peaks are *not* a "specular highlights", and

I didn’t say they were. Do you ever pay attention? You can’t even follow when I’m addressing your argument!

There are *no* specular hightlights in the images shown.

You know, logically if what you said made sense the
article would have discussed it in some way, but it does not even hint at it. If changing the contrast displayed a more accurate *exposure* (right edge location), why
didn’t they point to it?

"What does all this mean? In order to display the full dynamic range of your camera in the histogram displayed on the back, you must set the contrast to minimum. You now can see the same dynamic range in the histogram on the camera as you will see it in your RAW processor on your computer."

Nice switcheroo, but the article that shows the histograms says nothing like that. Here is what it says, in it’s entirety:

"Contrast adjustment

Adjusting the tone alters the shape of the ‘S curve’
used to map the linear image data captured by the
sensor into the correct gamma. A lower contrast
setting maintains more of the original data’s dynamic
range but leads to a flatter looking image. A higher
contrast setting stretches the grayscale (dark to
light) of the image and could lead to clipping of both
shadow detail and highlights. The Neutral Picture
Style was used for the samples below."

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

Paul Furman wrote:

Floyd L. Davidson wrote:

Paul Furman wrote:

Floyd L. Davidson wrote:

That is exactly the point I *am* making. WB changes
the histogram in a useful way. The Luminous-Landscape
article did not talk about WB at all. They discussed
changing the camera’s setting for contrast, and that
simply does *nothing* useful for the histogram/exposure
issue. And if you doubt that the contrast setting will not change the histogram as stated, *try* *it*. I gave an step by step description of a very easy way to show exactly what does and does not happen. Why argue from supposition when you could actually learn something about photography…

I am interested in learning. I tried fiddling with
the camera contrast
settings to compare histograms and the difference was very minor, at least for the conditions I tried just now.

A second try showed a significant difference.

I was thinking of
post-processing where increasing contrast blows highlights & blocks shadows. Maybe not the very final edge of 100% saturation but contrast adjustments can make a big difference in what appears to be blown or blocked. What you are describing sounds more like a gamma adjustment than contrast where only the middle part shifts.

Scratch that comment, they both have an effect.

"Gamma is equivalent to contrast.

I dunno, maybe your linked definers are thinking of a different context.

I would expect that both Norman Koren and HP do know exactly what gamma and contrast are. The context is *exactly* the one we are discussing.

Common sense and experience tell me gamma is adjusting the middle-value, more like brightness, without changing the the ends.

A generalization, but not wrong.

Contrast
adjustments tend to hold the mid-point and use an s curve to raise highlights & lower shadows or the inverse.

Not true. Contrast is the slope of the curve.

A gamma adjustment curve is a
fairly simple bowed shape, not an s shape.

Not necessarily.

Sure a gamma adjustment has
an effect on contrast but that’s a side effect, not the goal. Gamma adjustments boost contrast in either the highlights or shadows, not both.

Not necessarily.

This can be observed
in traditional film curves, which are displayed on
logarithmic scales (typically, density (log10(absorbed
light) vs. log10(exposure)). Gamma is the average
slope of this curve (excluding the "toe" and
"shoulder" regions near the ends of the curve), i.e., the contrast."
http://www.imatest.com/docs/glossary.html
(The above is a web page owned by Norman Koren.)
"Gamma — A way of representing the contrast of an
image, shown as the slope of a curve showing tones
from white to black."
http://www.hp.com/united-states/consumer/digital_photography /articles/scanner_glossary.html That might help make things clearer as to why changing
contrast does not make the histogram any more or less
accurate for exposure.
When the histogram indicates precisely the correct
exposure, changing the gamma (contrast) moves the curve
between black and maximum white values, but it doesn’t
change the value of either. Note too that it might
spread the histogram out from the center (if the gamma
curve is moved by picking a point at its center), or it
might move towards ether the right or the left (if the
gamma curve is moved from point closer to the ends
instead of at the center).
In any case, it changes the contrast but if there are
image values at the maximum white value they will not be moved.

The maximum white value may be already off the edge so you are talking about part of the middle of the curve, which is effected, showing more detail with low contrast.

Maximum white values cannot go "off the edge". They go *to the edge*, and no higher. The maximum value does not change, though the number of pixels that have that value might change.

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

I don’t use those programs so I can only provide
general
instructions about how that is typically done. I’ll
leave it to someone who can be more specific.

Understanding this would help in simulating exposure changes in an editor – to better understand when shooting & interpreting the histogram.

Yes, you will certainly find it useful.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 8, 2009

Porte Rouge wrote:

On Oct 8, 6:22 am, (Floyd L. Davidson) wrote:

Paul Furman wrote:

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can
be a problem in dark areas…

The only cameras I know of with even a hint of RAW
posterization are the Pentax K10D, which would profit
from 13 bits instead of 12 at ISO 100 (not for 200 or
higher), the Sony A900 also with a need for 13 bits at
base, and the D3X when in 12-bit mode.  These are only
on the fringe of posterizing.

raising shadows in post for the deepest shadows, and
in skies where the color pallet is very
limited. Doesn’t the noise level follow this same
principle? Or is there an unrelated reason for the
noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most
likely caused by the math used in the converter, and
nothing else.  Of course, JPEG compression does some
posterization of its own, especially if you use too
much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS.http://www.luminous-landscape.com/tutorials/expose-right. shtml

That is an *excellent* article.  It also has a link to
another article, titled "Understanding Histograms", which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

Porte Rouge

Oct 8, 2009

On Oct 8, 2:36 pm, (Floyd L. Davidson) wrote:

Porte Rouge wrote:

On Oct 8, 6:22 am, (Floyd L. Davidson) wrote:

Paul Furman wrote:

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can
be a problem in dark areas…

The only cameras I know of with even a hint of RAW
posterization are the Pentax K10D, which would profit
from 13 bits instead of 12 at ISO 100 (not for 200 or
higher), the Sony A900 also with a need for 13 bits at
base, and the D3X when in 12-bit mode.  These are only
on the fringe of posterizing.

raising shadows in post for the deepest shadows, and
in skies where the color pallet is very
limited. Doesn’t the noise level follow this same
principle? Or is there an unrelated reason for the
noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most
likely caused by the math used in the converter, and
nothing else.  Of course, JPEG compression does some
posterization of its own, especially if you use too
much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS.http://www.luminous-landscape.com/tutorials/expose-right. shtml

That is an *excellent* article.  It also has a link to
another article, titled "Understanding Histograms", which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

floyd

Oct 8, 2009

Porte Rouge wrote:

On Oct 8, 2:36 pm, (Floyd L. Davidson) wrote:

Porte Rouge wrote:

On Oct 8, 6:22 am, (Floyd L. Davidson) wrote:

Paul Furman wrote:

John Sheehy wrote:

Paul Furman wrote:

OK, the noise is more the reason but posterizing can
be a problem in dark areas…

The only cameras I know of with even a hint of RAW
posterization are the Pentax K10D, which would profit
from 13 bits instead of 12 at ISO 100 (not for 200 or
higher), the Sony A900 also with a need for 13 bits at
base, and the D3X when in 12-bit mode.  These are only
on the fringe of posterizing.

raising shadows in post for the deepest shadows, and
in skies where the color pallet is very
limited. Doesn’t the noise level follow this same
principle? Or is there an unrelated reason for the
noise levels paralleling tone counts?

Any posterization you see in a RAW conversion is most
likely caused by the math used in the converter, and
nothing else.  Of course, JPEG compression does some
posterization of its own, especially if you use too
much NR and it starts blocking up.

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS.http://www.luminous-landscape.com/tutorials/expose-right. shtml

That is an *excellent* article.  It also has a link to
another article, titled "Understanding Histograms", which several contributors to this thread could benefit
from (particularly the histogram of the moon shot and
the high key tree image that are the last two shown at
the bottom of the article):

John McWilliams

Oct 8, 2009

Clues wrote:

On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy wrote:

Exposure to the right is usually given as advice for RAW shooting. The RAW data usually clips well above the level where a JPEG would clip it,

Very true, for all those cameras that intentionally do a poor job at the RAW to JPG conversion. This is why RAW became so popular. DSLRs are inherently poor at this process. In fact it’s the very reason that having access to the RAW data became so popular. Far too many DSLR owners wanted to repair in their resulting images what the DSLR’s firmware programmers failed to do correctly in the first place. Companies then realized that they could turn this into an asset. Not only sell a camera that didn’t work quite right, bundled with a kit-lens that wouldn’t provide images any better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to make their $500 DSLR functional, but now also sell them expensive editing software to fix what their cameras weren’t doing properly to provide a useful image right out of the box.

‘Ceptin’ the major camera mfg’s provide software with the purchaseof the camera, and excellent lenses can be had for a mere grand. One or two {Nikon} may also try to sell "Pro" RAW converters.

Most in-camera conversion for JPEGs is above very decent, and is excellent for daylight/time normal exposures.

—
john mcwilliams

floyd

Oct 9, 2009

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 9, 2009

Doug McDonald wrote:

I have performed tests on my Canon 30D camera to see
what happens if I expose less. I exposed 1/3 and 2/3
stops less than before.

At 2/3 stop less than before yes, even at contrast setting zero, I do see a teensy bit of space between the top of the red histogram and the top of the display. This means that if I’m willing to lose 2/3 stop of unclipped data at the bright end, Floyd is "effectively" right.

But if I want that extra 2/3 stop, I’m still correct.

You have verified that you can’t read a histogram, and
that what I’ve previously said is true. Changing
contrast isn’t helping you a bit, but WB adjustment
would make your histogram more accurate, as well as make your preview JPEG image greenish.

Your description suggests that at 0 EC your histogram
was indicating you should be clipping. The red channel
though, due to WB adjustment, is typcially about 1/2 to
3/4 of an fstop higher in the JPEG than it is in the raw data. (Look in the Exif data and to find out what the
red channel multiplier is, and you can calculate exactly what the fstop value differential is.)

To *correct* the inaccuracy of your histogram you can
adjust the WB to be more greenish. That will reduce the red channel in the JPEG to agree with the raw data.

Changing contrast does *not* change the histogram’s
representation of exposure, and therefore *cannot* make
the histogram more accurate. Only WB adjustment will do that for you.

I should add that my method works — I use -4 in the camera, use the histogram, and find my raw images are very nicely exposed, no clipping (except as desired for specular highlights) and the data right up to the clipping level.

All you are doing is misunderstanding the histogram, and because the WB adjustment gives you 1/2 to 3/4 of an
fstop of leeway, you end up with useful results. It is
very unlikely that you have the technical expertize to
even determine how close your raw data is to clipping,
never mind being able to see any difference in losing
that amount of dynamic range at the low end of the
exposure range as a result of the inaccurate histogram.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 9, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

Yes, they do, in terms of *accuracy*.

You simply do not know how to read a histogram, and until you learn there is little point in talking to you on any topic that requires it.

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

rfischer

Oct 9, 2009

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

You’re trying to change the subject.

—
Ray Fischer

floyd

Oct 9, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

Yes, they do, in terms of *accuracy*.

You simply do not know how to read a histogram, and until you learn there is little point in talking to you on any topic that requires it.

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I’m saying is unique. Everyone who does understand it says
basically the same things…

Here is a tutorial that explains how to get an accurate
histogram.

<http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm>

As for reading histograms, I don’t know of any tutorials that don’t have at least some errors, but this one is
pretty good:

< http://www.luminous-landscape.com/tutorials/understanding-se ries/understanding-histograms.shtml>

This tutorial is a pretty good one for learning how to use ETTR:

< http://www.luminous-landscape.com/tutorials/expose-right.sht ml>

If you want a lot of detail, do a google search on Iyla Borg and "white balance" or "histogram".

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 9, 2009

(Ray Fischer) wrote:

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

You’re trying to change the subject.

*Narrowing* the subject.

It is exceedingly difficult to discuss histograms with
people who do not understand what a histogram shows and
how to read it.

Until we get all participants on the same sheet when it
comes to how to read a histogram there simply isn’t much point in discussing the other aspects of their use, eh?

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

kd

Oct 9, 2009

On Thu, 08 Oct 2009 14:14:55 -0700, John McWilliams
wrote:

Clues wrote:

On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy wrote:

Exposure to the right is usually given as advice for RAW shooting. The RAW data usually clips well above the level where a JPEG would clip it,

Very true, for all those cameras that intentionally do a poor job at the RAW to JPG conversion. This is why RAW became so popular. DSLRs are inherently poor at this process. In fact it’s the very reason that having access to the RAW data became so popular. Far too many DSLR owners wanted to repair in their resulting images what the DSLR’s firmware programmers failed to do correctly in the first place. Companies then realized that they could turn this into an asset. Not only sell a camera that didn’t work quite right, bundled with a kit-lens that wouldn’t provide images any better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to make their $500 DSLR functional, but now also sell them expensive editing software to fix what their cameras weren’t doing properly to provide a useful image right out of the box.

‘Ceptin’ the major camera mfg’s provide software with the purchaseof the camera, and excellent lenses can be had for a mere grand. One or two {Nikon} may also try to sell "Pro" RAW converters.
Most in-camera conversion for JPEGs is above very decent, and is excellent for daylight/time normal exposures.

If your camera’s resulting JPG file’s dynamic range does not closely match the dynamic range of your RAW data, then there’s something obviously very wrong with your camera, your camera’s settings, or you.

(To enlighten the ignorant: There is zero difference in the amount of noise in a 2 minute exposure in low light and a 1/2000s exposure in bright light. Photons are photons. If you collect enough to get over the base noise-threshold then all those parts of the image that are properly exposed will be noise-free in any image, no matter the initial light levels.)

sigh

Oct 9, 2009

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Nothing can be determined from either without the accompanying photograph. This is why I find histograms so useless. A much better option is a viewfinder that displays in real-time the under/over-exposed areas of your subject and its composition. Only then will you know what parts of your subject you can devote to which range of your sensor.

Since these are merely luminance histograms (not RGB) your first one only shows that you have saturated one of the RGB channels in the low-midtones. Most likely the blue channel. It says absolutely nothing about that being the proper exposure for the subject or not. The subject could very well be displayed best with that location and shape of histogram.

The second one it only shows that most of your image was lighter luminance values. Not if they were properly distributed or not. It could be a scene of a white shell on a sunlit beach with little to no shadows at all, nor required. A perfectly fine image, exposed properly. We’ll never know, because your histogram is not compared to a real image. Reading histograms alone is useless information.

A good analogy would be someone who was baking a cake. They need ozs. and lbs. of sugar and flour. Without the sugar and flour and knowing how you want your final cake to taste, you’ll never know if arguing about the 1/1000th of an oz. or the 2.320111633 lbs. is appropriate or not for that cake. Your units of measure are meaningless information when taken out of context from real-world requirements and conditions. Some of the best cooks in the world don’t even measure at all. (I rarely do, I cook by taste and texture, never had a failed meal yet.)

Histograms are fairly useless when it comes right down to it. They are only the mental-masturbation playthings of snapshooting tech-heads. If they weren’t arguing about histogram reading, they’d be arguing about the proper capacitance value on the high-frequency filter of their $16,000 stereo’s circuit board. Never mind the photography, nevermind the music, histograms and capacitor values are more important to them. They can’t see the images, they can’t hear the music. All of that is far beyond their comprehension.

rfischer

Oct 9, 2009

Kyle D. wrote:

On Thu, 08 Oct 2009 14:14:55 -0700, John McWilliams
wrote:

Clues wrote:

On Wed, 07 Oct 2009 17:19:12 -0500, John Sheehy wrote:

Exposure to the right is usually given as advice for RAW shooting. The RAW data usually clips well above the level where a JPEG would clip it,

Very true, for all those cameras that intentionally do a poor job at the RAW to JPG conversion. This is why RAW became so popular. DSLRs are inherently poor at this process. In fact it’s the very reason that having access to the RAW data became so popular. Far too many DSLR owners wanted to repair in their resulting images what the DSLR’s firmware programmers failed to do correctly in the first place. Companies then realized that they could turn this into an asset. Not only sell a camera that didn’t work quite right, bundled with a kit-lens that wouldn’t provide images any better than a Barbie-Cam, conning them into buying a $5,000-$10,000 lens to make their $500 DSLR functional, but now also sell them expensive editing software to fix what their cameras weren’t doing properly to provide a useful image right out of the box.

‘Ceptin’ the major camera mfg’s provide software with the purchaseof the camera, and excellent lenses can be had for a mere grand. One or two {Nikon} may also try to sell "Pro" RAW converters.
Most in-camera conversion for JPEGs is above very decent, and is excellent for daylight/time normal exposures.

If your camera’s resulting JPG file’s dynamic range does not closely match the dynamic range of your RAW data, then there’s something obviously very wrong with your camera, your camera’s settings, or you.

(To enlighten the ignorant: There is zero difference in the amount of noise in a 2 minute exposure in low light and a 1/2000s exposure in bright light. Photons are photons. If you collect enough to get over the base noise-threshold then all those parts of the image that are properly exposed will be noise-free in any image, no matter the initial light levels.)

But electron noise is a function of time and temperature. The longer the exposure the more opportunity there is for electrons to party.

—
Ray Fischer

rfischer

Oct 9, 2009

Floyd L. Davidson wrote:

(Ray Fischer) wrote:

Floyd L. Davidson wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

You’re trying to change the subject.

*Narrowing* the subject.

It is exceedingly difficult to discuss histograms with
people who do not understand what a histogram shows and
how to read it.

People such as yourself, for example.

—
Ray Fischer

DRS

Oct 9, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I’m saying is unique. Everyone who does understand it says
basically the same things…

Except you. Go read your own tutorials. I already have.

floyd

Oct 9, 2009

sigh… wrote:

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Nothing can be determined from either without the accompanying photograph. This is why I find histograms so useless. A much better option is a viewfinder that displays in real-time the under/over-exposed areas of your subject and its composition. Only then will you know what parts of your subject you can devote to which range of your sensor.

Since these are merely luminance histograms (not RGB) your first one only shows that you have saturated one of the RGB channels in the low-midtones. Most likely the blue channel. It says absolutely nothing about that being the proper exposure for the subject or not. The subject could very well be displayed best with that location and shape of histogram.
The second one it only shows that most of your image was lighter luminance values. Not if they were properly distributed or not. It could be a scene of a white shell on a sunlit beach with little to no shadows at all, nor required. A perfectly fine image, exposed properly. We’ll never know, because your histogram is not compared to a real image. Reading histograms alone is useless information.

A good analogy would be someone who was baking a cake. They need ozs. and lbs. of sugar and flour. Without the sugar and flour and knowing how you want your final cake to taste, you’ll never know if arguing about the 1/1000th of an oz. or the 2.320111633 lbs. is appropriate or not for that cake. Your units of measure are meaningless information when taken out of context from real-world requirements and conditions. Some of the best cooks in the world don’t even measure at all. (I rarely do, I cook by taste and texture, never had a failed meal yet.)

Histograms are fairly useless when it comes right down to it. They are only the mental-masturbation playthings of snapshooting tech-heads. If they weren’t arguing about histogram reading, they’d be arguing about the proper capacitance value on the high-frequency filter of their $16,000 stereo’s circuit board. Never mind the photography, nevermind the music, histograms and capacitor values are more important to them. They can’t see the images, they can’t hear the music. All of that is far beyond their comprehension.

Histograms are *absolutely* useless… to people who do not understand them.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 9, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I’m saying is unique. Everyone who does understand it says
basically the same things…

Except you. Go read your own tutorials. I already have.

Do it again. The point is to understand. You don’t.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 9, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I’m saying is unique. Everyone who does understand it says
basically the same things…

Except you. Go read your own tutorials. I already have.

Do it again. The point is to understand. You don’t.

So you say. Whatever. Get a life.

floyd

Oct 9, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

According to you. Not according to everybody else. You maintain you’re the only one here who understands what’s going on but that’s not supported by the evidence so I’m quite happy to let you drift off in your fantasy world.

The evidence is rather extensive, and nothing I’m saying is unique. Everyone who does understand it says
basically the same things…

Except you. Go read your own tutorials. I already have.

Do it again. The point is to understand. You don’t.

So you say. Whatever. Get a life.

Well, it *is* rather obvious that if you’ve even looked
at the tutorials all you did was scan them.

In another article I posted URL’s to a pair of
histograms and asked what could be determined from them. So far the only response is from one person who first
says "nothing", and then proceeds to list a few things (and he did get at least some of it right too!).

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Let’s see *you* post an analysis of what they mean. I
don’t think you can.

But I’ll also invite your comments on what I have to
say, later. I’ll give everyone who wishes a chance to
do their own analyzing, and then I’ll post a lengthy
analysis of each. I’ll also give instructions on how to generate, with an editor, an image with a very similar
histogram in order to demonstrate what the significant
characteristics of each histogram actually are. And
(I’ll post URL’s for the actual images that those
histograms are related to.)

You are welcome to take a shot at it; assuming you
actually do think you know something about histograms,
here’s your chance to show it. My bet is that you won’t even try, because you are well aware that histograms
don’t mean much to you.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

DRS

Oct 9, 2009

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

So you say. Whatever. Get a life.

Well, it *is* rather obvious that if you’ve even looked
at the tutorials all you did was scan them.

In another article I posted URL’s to a pair of
histograms and asked what could be determined from them. So far the only response is from one person who first
says "nothing", and then proceeds to list a few things (and he did get at least some of it right too!).

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Let’s see *you* post an analysis of what they mean. I
don’t think you can.

I recognised those histograms from the LL article on histograms without even checking. I remembered the first as the night shot (hence the predominance of pixels towards the left) with the moon (hence the smattering of pixels to the right). I remembered the second one as the snow shot, hence the total right-shift in the pixels. Big deal. I know why they look like they do and I know it has nothing whatever to do with the very, very simple point I and others have been insisting on and which you alone are denying (and wrongly at that since you don’t know half as much as you think you do). As I said, get a life, and stop lecturing people on subjects you only half understand.

floyd

Oct 9, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

So you say. Whatever. Get a life.

Well, it *is* rather obvious that if you’ve even looked
at the tutorials all you did was scan them.

In another article I posted URL’s to a pair of
histograms and asked what could be determined from them. So far the only response is from one person who first
says "nothing", and then proceeds to list a few things (and he did get at least some of it right too!).

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Let’s see *you* post an analysis of what they mean. I
don’t think you can.

I recognised those histograms from the LL article on histograms without even checking. I remembered the first as the night shot (hence the predominance of pixels towards the left) with the moon (hence the smattering of pixels to the right). I remembered the second one as the snow shot, hence the total right-shift in the pixels. Big deal. I know why they look like they do and I know it has nothing whatever to do with the very, very simple point I and others have been insisting on and which you alone are denying (and wrongly at that since you don’t know half as much as you think you do). As I said, get a life, and stop lecturing people on subjects you only half understand.

Well, that certainly is one point in your favor! You
actually did recognize what they are. Of course you are wrong about them not having anything to do with what we
have been discussing (indeed, they are part of the
tutorial on histograms *because* they relate to what
we’ve discussed).

Again, I take it the reason *you* cannot provide any
indication of what the significance of those two
particular histograms is, is simply that you don’t know. So much for you claiming to know all there is about
histograms!

And do note that later today I’ll post an extensive analysis of each, showing exactly what can be understood from them.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

rfischer

Oct 9, 2009

Floyd L. Davidson wrote:

"DRS" wrote:

"Floyd L. Davidson" wrote in message

"DRS" wrote:

[…]

So you say. Whatever. Get a life.

Well, it *is* rather obvious that if you’ve even looked
at the tutorials all you did was scan them.

In another article I posted URL’s to a pair of
histograms and asked what could be determined from them. So far the only response is from one person who first
says "nothing", and then proceeds to list a few things (and he did get at least some of it right too!).

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Let’s see *you* post an analysis of what they mean. I
don’t think you can.

I recognised those histograms from the LL article on histograms without even checking. I remembered the first as the night shot (hence the predominance of pixels towards the left) with the moon (hence the smattering of pixels to the right). I remembered the second one as the snow shot, hence the total right-shift in the pixels. Big deal. I know why they look like they do and I know it has nothing whatever to do with the very, very simple point I and others have been insisting on and which you alone are denying (and wrongly at that since you don’t know half as much as you think you do). As I said, get a life, and stop lecturing people on subjects you only half understand.

Well, that certainly is one point in your favor! You
actually did recognize what they are. Of course you are wrong about them not having anything to do with what we
have been discussing (indeed, they are part of the
tutorial on histograms *because* they relate to what
we’ve discussed).

Again, I take it the reason *you* cannot provide any
indication of what the significance of those two

So farall YOU have been able to do is insist that you’re right and everybody else is wrong. Needless to say, that’s never a very convincing argument.

—
Ray Fischer

Alan Browne

Oct 9, 2009

sigh… wrote:

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Doug McDonald wrote:

Floyd L. Davidson wrote:

Hence if the right edge is set correctly with high
contrast or low contrast, either way it is exactly the
same exposure and neither is more accurate than the
other.
You continue to say that low contrast makes it easier
to
see where the edge is, but that is only true for special cases, and for an equal number of special cases high
contrast would make it easier!

In NO CASE would high contrast make it easier …
at least on a Canon 30D.

Mr. Davidson: Let me ask again: What is the serial
number of the Canon 30D you have checked this on.

If you have not done so, SHUT UP.

We admit that you are right if somebody using
a Canon 30D is willing to allow 2/3 stop more "slop" than is really necessary.

It does not appear that you understand how to read a
histogram.

Hmmm… tell me what you make of these two histograms:

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Nothing can be determined from either without the accompanying photograph.

BS. It’s clear that the first one was mostly shadow, probably a black card (or underexposed grey card). There may have been a shiny patch, or perhaps a white edge to explain the bumps on the right…

The second a white card (or over exposed grey card).

This is so easy to replicate…

A near nominal exposed grey card will give a lump in the middle.

Hilarity Ensues

Oct 9, 2009

On Fri, 09 Oct 2009 10:44:52 -0800, (Floyd L. Davidson) wrote:

And do note that later today I’ll post an extensive analysis of each, showing exactly what can be understood from them.

Oh, this is going to be good. Let me go get some popcorn, and a milkshake. So when I laugh real hard the milkshake will come streaming out of my nose.

DRS

Oct 9, 2009

"Alan Browne" wrote in message

sigh… wrote:

[…]

Nothing can be determined from either without the accompanying photograph.

BS. It’s clear that the first one was mostly shadow, probably a black card (or underexposed grey card). There may have been a shiny patch, or perhaps a white edge to explain the bumps on the right…

It was a night shot landscape with a blue cast. The moon provide the smattering of pixels on the right.

The second a white card (or over exposed grey card).

It was a snow-laden tree surrounded by snow. The image had a hint of fog. All those whites and light grays predictably pushed everything over to the right.

This is so easy to replicate…

True. And it also manages to avoid the point (not you, Floyd).

Alan Browne

Oct 9, 2009

DRS wrote:

"Alan Browne" wrote in message

sigh… wrote:

[…]

Nothing can be determined from either without the accompanying photograph.

BS. It’s clear that the first one was mostly shadow, probably a black card (or underexposed grey card). There may have been a shiny patch, or perhaps a white edge to explain the bumps on the right…

It was a night shot landscape with a blue cast. The moon provide the smattering of pixels on the right.

The second a white card (or over exposed grey card).

It was a snow-laden tree surrounded by snow. The image had a hint of fog. All those whites and light grays predictably pushed everything over to the right.

The above being so, it could just as easily have been black or white cards in "nominal" exposure or grey cards exposed as I described.

With little fuss I could replicate your histos (close enough) in a few minutes and with a variety of exposure methods. Anyone could. Well, maybe not Floyd.

This is so easy to replicate…

True. And it also manages to avoid the point (not you, Floyd).

Porte Rouge

Oct 9, 2009

On Oct 8, 3:04 pm Floyd L. Davidson wrote

"which is ridiculous!"

It is. My apologies. I miss aligned the thread and saw the other link. Also, I could not see that all the messages in the thread were being forwarded. Google Groups hides them in the posts.

Porte

Charles

Oct 9, 2009

A link for your enjoyment.

http://www.rags-int-inc.com/PhotoTechStuff/ETTR/

John McWilliams

Oct 9, 2009

Kyle D. wrote:

(To enlighten the ignorant: There is zero difference in the amount of noise in a 2 minute exposure in low light and a 1/2000s exposure in bright light. Photons are photons. If you collect enough to get over the base noise-threshold then all those parts of the image that are properly exposed will be noise-free in any image, no matter the initial light levels.)

Bzzzzt!
Flat out wrong.

—
lsmft

Wilba

Oct 10, 2009

Paul Furman wrote:

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

Image | Adjustments | Exposure… ?

Mike Russell

Oct 10, 2009

On Sat, 10 Oct 2009 08:09:45 +1100, DRS wrote:

"Alan Browne" wrote in message

sigh… wrote:

[…]

Nothing can be determined from either without the accompanying photograph.

BS. It’s clear that the first one was mostly shadow, probably a black card (or underexposed grey card). There may have been a shiny patch, or perhaps a white edge to explain the bumps on the right…

It was a night shot landscape with a blue cast. The moon provide the smattering of pixels on the right.

The second a white card (or over exposed grey card).

It was a snow-laden tree surrounded by snow. The image had a hint of fog. All those whites and light grays predictably pushed everything over to the right.

This is so easy to replicate…

True. And it also manages to avoid the point (not you, Floyd).

LOL – zing!
—
Mike Russell – http://www.curvemeister.com

Wilba

Oct 10, 2009

Porte Rouge wrote:

Wilba wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the
left, so that’s a waste of time. To avoid having the deep colours washed out, you need to make use of the full tonal range available in the image. If
you have done a good job of exposing to the right, your highlights will be
pretty much where they need to be. So then all you need to do is raise the
black point (e.g. using the Levels dialog in Photoshop), so that the dark tones in the scene end up as dark tones in the image. If you are using the
Levels dialog in Photoshop, while you drag the black (or white) point slider, press the Alt key to see which pixels are clipped (or blown).
(The following relates to my experience with a Canon 450D. YMMV.)

Aha!

:- ) Was that what you actually wanted to know?

There are two parts to exposing to the right – levels in the image and saturation of photosites. Whether you are shooting JPEG or raw, the camera’s
histogram display shows you the levels in a JPEG produced from the raw data,
so the shape of the histogram curve depends on your settings for sharpness,
contrast, saturation, colour tone, etc.

And white balance, of course.

If you are shooting JPEG, all you can do is avoid piling up the histogram on
the right, which prevents gross areas of blown highlights in the image.
If you are shooting raw, you can overexpose (beyond the point at which the
histogram curve touches the right boundary), by about two steps and still produce an image from the raw without blown highlights. IOW, the headroom between blown highlights in the JPEG and saturation of the photosites is about two steps (in my experience, with the JPEG settings I use).
So if you are bracketing for the best possible exposure, go at least two steps over what the histogram tells you is "correct". The maximum possible
dynamic range occurs at the point where photosites in the highlights begin
to saturate.

What do you mean by steps? Do you mean stops, or steps on the aperture or shutter dials?

No, nothing to do with the increments by which the camera’s controls change the exposure – that’s arbitrary. An exposure step is a doubling or halving of the amount of light that reaches the sensor. A stop is a step achieved via the aperture. Most people also say stop when they mean a step achieved via the shutter.

In everyday raw shooting, you can be quite relaxed about having a small spike on the right of the histogram – that’s actually a good thing.

floyd

Oct 10, 2009

"Wilba" wrote:

Porte Rouge wrote:

Wilba wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the
left, so that’s a waste of time. To avoid having the deep colours washed out, you need to make use of the full tonal range available in the image. If
you have done a good job of exposing to the right, your highlights will be
pretty much where they need to be. So then all you need to do is raise the
black point (e.g. using the Levels dialog in Photoshop), so that the dark tones in the scene end up as dark tones in the image. If you are using the
Levels dialog in Photoshop, while you drag the black (or white) point slider, press the Alt key to see which pixels are clipped (or blown).
(The following relates to my experience with a Canon 450D. YMMV.)

Aha!

:- ) Was that what you actually wanted to know?

None of it is correct though. What do you get, for example, if you shoot a image that is mostly an 18% gray card, against a black background?

If you use ETTR to get the most dynamic range, the gray card will show up as very close to maximum white in the raw data.

"If you have done a good job of exposing to the right, your highlights will be pretty much where they need to
be. So then all you need to do is raise the black
point (e.g. using the Levels dialog in Photoshop), so
that the dark …"

Obviously that is not true. The only time it will be
true is when there actually *are* highlights that are
"pretty much" at pur white. Not all scenes have such highlights, and therefore not all image data will have
them "pretty much where they need to be".

And that is when you use a raw converter or an editor
for "reducing the exposure in Lightroom just puts your histogram back to the left.", and it clearly is *not* a waste of time.

….

So if you are bracketing for the best possible exposure, go at least two steps over what the histogram tells you is "correct". The maximum possible
dynamic range occurs at the point where photosites in the highlights begin
to saturate.

What do you mean by steps? Do you mean stops, or steps on the aperture or shutter dials?

No, nothing to do with the increments by which the camera’s controls change the exposure – that’s arbitrary. An exposure step is a doubling or halving of the amount of light that reaches the sensor. A stop is a step achieved via the aperture. Most people also say stop when they mean a step achieved via the shutter.

Yes, they usually say that because in fact it is the
same thing in the context that you have described, it
changes the amount of light reaching the sensor.

And how you can say "nothign to do with the increments by which the camera’s controls change the exposure" and then describe camera controls changing the
exposure… is amusing.

In everyday raw shooting, you can be quite relaxed about having a small spike on the right of the histogram – that’s actually a good thing.

It is, assuming you want to clip the highlights.
Otherwise, it’s a fatal error, because there is no way
to recover the lost data. On the other hand, if you
back off on exposure just enough to make sure no
highlights are clipped, the loss of 1/2 to 1 stop of
dynamic range probably will mean absolutely nothing
(given that you won’t print out anything that can show
more than 5 or 6 fstops and the camera will almost
certainly be recording 8 or more).

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 10, 2009

"Charles" wrote:

A link for your enjoyment.

http://www.rags-int-inc.com/PhotoTechStuff/ETTR/

Yah gotta admit, that one is great entertainment. There multiple whole paragraphs where he gets nothing right!

He’s also got two links at the bottom of that page, both of which are equally a riot to read.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

floyd

Oct 10, 2009

sigh… wrote:

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Hmmm… tell me what you make of these two histograms:

<http://tinyurl.com/493fyp>
<http://tinyurl.com/4l8lle>

Nothing can be determined from either without the accompanying photograph.

Didn’t this turn out to be indicative! Not one of the
folks who made so many claims about understanding
histograms can even come up with comments on the article I’m responding to, much less put their own analysis
forward. DRS at least figured out where the histograms
came from, and was willing to repeat the very simple
characteristics. Alan Browne went a little farther and
did manage to not make any mistakes either. But none of were anything past the most cursory look, and none
provided any *useful* information.

The article that I am replying to, despite starting with a grossly incorrect statement (above), which he then
contradicted by giving an analysis, at least was an
effort. There are several mistakes though, but it *is*
a good effort.

This is why I find histograms so useless. A much better option is a viewfinder that displays in real-time the under/over-exposed areas of your subject and its composition. Only then will you know what parts of your subject you can devote to which range of your sensor.

That is true! But misses the point too, because the
highlight display is derived directly from the
histogram, and anything that makes the histogram more or less accurate also makes the highlight display more
accurate. Hence this discussion directly relates to how accurately one can set exposure using the highlight
display to the same degree that it relates to histogram
accuracy.

Setting in camera contrast adjustments will *not* make
the highlight display more or less accurate. It also
will not do that for the histogram either.

Setting White Balance will have a dramatic effect of the accuracy of both.

Understanding histograms makes that statement rather obvious, and while DRS and others wanted to get into childish games of claiming they know histograms, note that none of them is able to prove it with an easy analysis of a couple of very neat histograms!

Since these are merely luminance histograms (not RGB) your first one only shows that you have saturated one of the RGB channels in the low-midtones.

It shows no such thing. The vertical scale of the
histogram is almost certainly adjusted with auto-ranging in the software, but what it means is that the entire
*area* of the image is taken up with those tones. They
are not "saturated".

But there is something interesting about the shape of
that peak! Note that it is a trapezoid, with an almost
squared off top. The indication that provides is that
we probably have a picture of a distant black sky (which explains the flat top and the angled sides). Almost
nothing else produces the shape. (Think about that for
awhile, and the reason is obvious.)

Most likely the blue channel. It says absolutely nothing about that being the proper exposure for the subject or not. The subject could very well be displayed best with that location and shape of histogram.

That is true! Unfortunately you seem to have missed the other values in the histogram, which do relate to
exposure. (Note too that this is an histogram generated in post processing, not in the camera.) There is a line of pixels at the bottom of the display 1 to 3 pixels
high, running up to something about 1 fstop below
maximum white. Those are the pixels to look at to set
exposure. If this were a camera generated histogram one would want to increase exposure to help reduce noise
back over there on the left side where the large peak
is. But this is actually a editor’s histogram, and the
desired white level was not at maximum white, so the
"brightness" was reduced with the effect that all levels, including noise were reduced.

That is, the camera was exposed to get maximum dynamic
range, and the brightness was reduced in the editor to
retain that dynamic range. If the camera exposure had
been reduced by that amount the noise would not have
gone down when the signal did, and a lower dynamic range would have been recorded.

That is the advantage of using Expose To The Right.

The second one it only shows that most of your image was lighter luminance values. Not if they were properly distributed or not. It could be a scene of a white shell on a sunlit beach with little to no shadows at all, nor required. A perfectly fine image, exposed properly. We’ll never know, because your histogram is not compared to a real image. Reading histograms alone is useless information.

Not really! You are of course very correct that it is a high key image. It is also set to slightly less than
maximum white, just as the other image was. Note also
the "comb" effects showing up on the brighter levels of the histogram… those pretty much indicate that someone has used the "contrast" control to stretch the tonal range for that part of the image.

To show exactly how much one can get *from* an
histogram, lets use an editor to *create* a pair of them that basically match the two above. The idea is that
this process removes those two specific images from the
information in the histograms. Rather than see that
information in the images, it can be seen as actions
within an editor.

The first one is very simple. Open a blank image,
select the entire image, and add a linear gradient fill
to it. The direction of the fill makes no difference,
but it must completely fill the area of the image. Pick a pair of colors that are relatively close (it’s easier
to use black and white, but it isn’t necessary). Try
#202020 and #404040 to get something very close to the
original histogram.

The distance between the two colors will determine the
width of the peak. The absolute values will determine
where the peak is located. If the entire area is
filled, the top will be flat. If a linear gradient is
used, the sides will be straight up and down. To make
the sides lean (for either a triangle or a trapezoid), a non-linear gradient is necessary. The top can also be
rounded by using the right non-linear gradient. The
exact location and width of the peak can be adjusted
using brightness and contrast. The contrast will,
however, honeycomb the shape if the tonal range is
expanded.

(And note that exactly the same procedure is used to
generate a starting point for either of the two
histograms.)

For the "moon shot", the next step is to select a relatively small area, say 1/10 the size of the whole
image. A square or rectangle will do (or any other
shape, as only the area is of any significance). If
that area is filled with a single color value a peak at
that value will show up on the histogram. If a gradient is used, it will be spread out as a line on the floor of the histogram. The ends of the line will be determined
by the two ending color values of the gradient, and the
height of the line will be determined by the percentage
of image area that it covers. Note that as the
percentage goes up… that first peak will go down.
With only that small area selected, it’s width and
position can be manipulated with the brightness and
contrast tools. (If the trapezoid is desired, use a
spherical gradient and draw it diametrically from one
corner to the opposite.)

The second image is only slightly more complex. Use the same technique to get a single peak, but it should be
roughly 1/2 stop below maximum white. (Rounding the top depends on what tools a given editor has for non-linear
gradients, so I can’t give a universal method to create
that.) To cause the top and right sides of the the peak
to become honey combed, use a rectangular selection that includes a little more than half the entire image,
selecting all of the brighter half. Use a brightness
adjustment to move it right and left, use a contrast
adjustment to get the honeycomb.

Obviously there *is* a huge volume of information
available in a histogram; and very little of it has
anything at all to do with setting exposure. E.g., the
*contrast* information does *not* help set exposure.

Just because somebody posted it on Luminous Landscape
doesn’t make it true. We might note that there are
dozens of web sites saying that ETTR will be more
accurate using a corrected White Balance, but only one
making this false claim about contrast. Also note that
while there are hundreds or thousands of sites
explaining ETTR, there are also a few that claim it’s
bogus.

But if one understands histograms, it isn’t really hard
to pick out the bogus information.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Alan Browne

Oct 10, 2009

Mike Russell wrote:

This discussion transcended any technical merit long ago, but here’s my two cents.

For both Nikon and Canon the histogram is based on converted channel RGB values, not raw sensor values.

By experiment I’ve confirmed this to be the same of Sony’s a900 (and I assume other models). That is to say that the histo changes characteristic based on changes of contrast or other settings.

I’d prefer, of course, that when I’m shooting in raw only (as I normally do) that the histo be based solely on the raw data.

The real question is, does it, "really" matter?

Excepting specular reflections and source highlights, as long as the rest of the histo is inside the post it would not make any difference in the end – esp. if the histo is broken out by RGB (as it is on my camera and most recent DSLR’s (at least the higher end ones)).

In the end one must use ones metering skills to complement histo observations, esp. as the former is pre-shot and the later is after the fact.

For shooting in changing light conditions, the meter trumps the histo.

Alan Browne

Oct 10, 2009

Wilba wrote:

Porte Rouge wrote:

Wilba wrote:

Porte Rouge wrote:

I set my exposure to slide the histogram to the right, without clipping ( when I have time), to capture the most tonal levels . So, now when I am editing the photos they are over exposed(not clipped). A sunrise is a good example. The deep colors are washed out. The obvious fix(to me anyway) in Lightroom or CS4 is to reduce the exposure. Now my question is, by reducing exposure in post, am I just ending up in the same place (histogram to the left) as if I had just ignored the histogram when I was shooting and set the exposure to properly expose the image using my light meter? I guess in short I am asking if Lightroom or CS4 loses tonal values when you reduce exposure in editing.

Yes, reducing the exposure in Lightroom just puts your histogram back to the
left, so that’s a waste of time. To avoid having the deep colours washed out, you need to make use of the full tonal range available in the image. If
you have done a good job of exposing to the right, your highlights will be
pretty much where they need to be. So then all you need to do is raise the
black point (e.g. using the Levels dialog in Photoshop), so that the dark tones in the scene end up as dark tones in the image. If you are using the
Levels dialog in Photoshop, while you drag the black (or white) point slider, press the Alt key to see which pixels are clipped (or blown).
(The following relates to my experience with a Canon 450D. YMMV.)

Aha!

:- ) Was that what you actually wanted to know?

There are two parts to exposing to the right – levels in the image and saturation of photosites. Whether you are shooting JPEG or raw, the camera’s
histogram display shows you the levels in a JPEG produced from the raw data,
so the shape of the histogram curve depends on your settings for sharpness,
contrast, saturation, colour tone, etc.

And white balance, of course.

If you are shooting JPEG, all you can do is avoid piling up the histogram on
the right, which prevents gross areas of blown highlights in the image.
If you are shooting raw, you can overexpose (beyond the point at which the
histogram curve touches the right boundary), by about two steps and still produce an image from the raw without blown highlights. IOW, the headroom between blown highlights in the JPEG and saturation of the photosites is about two steps (in my experience, with the JPEG settings I use).
So if you are bracketing for the best possible exposure, go at least two steps over what the histogram tells you is "correct". The maximum possible
dynamic range occurs at the point where photosites in the highlights begin
to saturate.

What do you mean by steps? Do you mean stops, or steps on the aperture or shutter dials?

No, nothing to do with the increments by which the camera’s controls change the exposure – that’s arbitrary. An exposure step is a doubling or halving of the amount of light that reaches the sensor. A stop is a step achieved via the aperture. Most people also say stop when they mean a step achieved via the shutter.

The original meaning of a stop comes form a"stop" plate with varied sized holes in it. Today that would be the "f-stop".

Otherwise a stop is a stop no matter how it is achieved. This is inherent in reciprocity.

Whether aperture, shutter speed, filters, light levels (control of flash or constant lighting by any means) it’s a "stop" (or fraction thereof).

Alan Browne

Oct 10, 2009

Charles wrote:

A link for your enjoyment.

http://www.rags-int-inc.com/PhotoTechStuff/ETTR/

While forcefully written and mostly (which means more than 50%) right, it contains vague or erroneous claims of source information.

For example: Claim: "The photographic design point is, has been, and will continue to be based on the middle gray tone. This is the basis of the sunny daylight f/16 rule. It is the reference point for all exposure metering systems. It is also ingrained into the CIE color matching functions and all color order systems. "

CIE 1931 makes no reference to sunny-16 nor to grey as control point (other than to say that grey is just another version of white).

JPS

Oct 10, 2009

Paul Furman wrote in
news:hajq5b$nt5$:

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure.

It shouldn’t be visible in any kind of exposure. My comments about the limit of the value of RAW bit depth or the number of RAW levels is based on torturous tests!

What about Floyd’s comment below that the
noise level remains the same but exposing to the right increases the signal so that overwhelms the noise?

The read noise (including any dark current) stays the same, in an absolute sense. In a relative sense, it changes. For shot noise, it changes in both an absolute sense *and* a relative sense.

That seems to tie the two
together in a comprehensible way. The LL link just makes a lot of sense, it can’t be complete BS.
http://www.luminous-landscape.com/tutorials/expose-right.sht ml

Well, the reasons given for the benefit are not correct. You could take one shot with normal exposure, and one with +1 EC, now using the top RAW stop, and the benefit would still be there if you quantized the top stop to 300 levels, instead of ~8000. According to my calculations and emulations, no current DSLR needs more than 300 levels for the top stop (some older models with few, large pixels may need about 325).

Alan Browne

Oct 10, 2009

Mike Russell wrote:

On Mon, 05 Oct 2009 15:23:57 -0800, Floyd L. Davidson wrote:
[re film’s "expose for shadows", digital’s "expose for the highlights"]

Actually, since film is a negative, the two are in fact
actually the same. Expose for the brightest range of the *recording* *mechanism*.

That just happens to be the dark areas of a scene with
film (where the negative is clear) and the bright areas
of a scene with an electronic sensor (the highest
voltage output).

No – both refer to areas of the scene. The full rule of thumb for film is "Expose for the shadows. Develop for the highlights". Exposing for the shadows establishes the area of minimum negative density, and development has a much greater effect on the highlights than the shadows.

As I’ve mentioned before in this thread, digital sensors resemble slide film, not negative.

For slide film, the "rule" has always been to expose for the highlights, not the shadows. Development (except for push/pull) is cast more or less in concrete.

Paul Furman

Oct 10, 2009

Wilba wrote:

Paul Furman wrote:

An interesting related issue I don’t understand is how the exposure slider works in Lightroom or ACR. I don’t know how to duplicate that effect in photoshop with curves, levels, etc. Those all do like you describe, moving the middle parts of the histogram but there isn’t an easy way I can see to shift the whole exposure. Hmm, the middle slider on levels comes close but still doesn’t match the effect.

Image | Adjustments | Exposure… ?

Hmph, CS1 doesn’t have that.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Porte Rouge

Oct 10, 2009

On Oct 10, 1:57 am, (Floyd L. Davidson) wrote:

And how you can say "nothign to do with the increments by which the camera’s controls change the exposure" and then describe camera controls changing the
exposure… is amusing.

I think he meant the increments on the controls are arbitrary(1/3, 1/2, or 1 stop for each click on the dials.

floyd

Oct 10, 2009

Porte Rouge wrote:

On Oct 10, 1:57 am, (Floyd L. Davidson) wrote:

And how you can say "nothign to do with the increments by which the camera’s controls change the exposure" and then describe camera controls changing the
exposure… is amusing.

I think he meant the increments on the controls are arbitrary(1/3, 1/2, or 1 stop for each click on the dials.

But that does happen to be *exactly* where the term "stop" came from.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Porte Rouge

Oct 10, 2009

I think he meant the increments on the controls are arbitrary(1/3, 1/2, or 1 stop for each click on the dials.

But that does happen to be *exactly* where the term "stop" came from.

I’ll let you and Alan figure out where "stop" came from.

The amount of change in exposure per click on the dials on my DSLR is arbitrary, I choose how much I want.

Wilba

Oct 10, 2009

Porte Rouge wrote:

I think he meant the increments on the controls are arbitrary(1/3, 1/2, or 1 stop for each click on the dials.

But that does happen to be *exactly* where the term "stop" came from.

I’ll let you and Alan figure out where "stop" came from.
The amount of change in exposure per click on the dials on my DSLR is arbitrary, I choose how much I want.

Right. And those increments have nothing to do with what I was talking about – you get that, don’t you? :- )

DRS

Oct 11, 2009

"Floyd L. Davidson" wrote in message

sigh… wrote:

[…]

Obviously there *is* a huge volume of information
available in a histogram; and very little of it has
anything at all to do with setting exposure. E.g., the
*contrast* information does *not* help set exposure.

Nobody ever said it did. That straw man with you are obsessed has been exploded several times. The only thing setting contrast to minimum does (in this context) is expand the histogram so that it more accurately depicts the dynamic range in the Raw image so that the photographer can make a more informed decision about what if anything to *subsequently* do to the exposure. Everybody can see it except you and that is the only claim that has been made for it (except by you).

floyd

Oct 11, 2009

"DRS" wrote:

"Floyd L. Davidson" wrote in message

sigh… wrote:

[…]

Obviously there *is* a huge volume of information
available in a histogram; and very little of it has
anything at all to do with setting exposure. E.g., the
*contrast* information does *not* help set exposure.

Nobody ever said it did.

Well, not more than 100 or so times in this thread.

That straw man with you are obsessed has been
exploded several times.

*What* *has* *been* *exposed* *is* *that* *you* *can’t* *cut* *the* *mustard*.

All those claims of knowning everything about
histograms, and when asked to give an analysis of two
examples you could not produce.

The only thing setting contrast to minimum does (in
this context) is expand the histogram so that it more accurately depicts the dynamic range in the Raw image so that the photographer can make a more informed decision about what if anything to *subsequently* do to the exposure.

You say "Nobody ever said it did", and then once again claim it does. What nobody has ever claimed is that
*anything* thing works until *subsequently* to an
exposure! Your remarks are illogical weasel words.

Everybody can see it except you and that is the only claim that has been made for it (except by you).

Everybody realizes that the process is to make an
exposure and then subsequently make exposure adjustments based on what the histogram shows before making another
exposure.

The problem is that setting the camera for low contrast
isn’t very useful, and might even make some (high key
image) histograms more difficult to read.

The *valid* way to make a histogram more useful is to
make it more accurate. That can be done by changing the White Balance adustment of the camera. (A fact you
would recognize if you actually understood what
histograms are.)

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Wilba

Oct 11, 2009

DRS wrote:

Floyd L. Davidson wrote:

Obviously there *is* a huge volume of information
available in a histogram; and very little of it has
anything at all to do with setting exposure. E.g., the
*contrast* information does *not* help set exposure.

Nobody ever said it did. That straw man with you are obsessed has been exploded several times. The only thing setting contrast to minimum does (in this context) is expand the histogram so that it more accurately depicts the dynamic range in the Raw image so that the photographer can make a more informed decision about what if anything to *subsequently* do to the exposure. Everybody can see it except you and that is the only claim that has been made for it (except by you).

Floyd is arguing with the demons in his head (and losing).

Is there anything else left to discuss amongst the rest of us?

floyd

Oct 11, 2009

"Wilba" wrote:

DRS wrote:

Floyd L. Davidson wrote:

Obviously there *is* a huge volume of information
available in a histogram; and very little of it has
anything at all to do with setting exposure. E.g., the
*contrast* information does *not* help set exposure.

Nobody ever said it did. That straw man with you are obsessed has been exploded several times. The only thing setting contrast to minimum does (in this context) is expand the histogram so that it more accurately depicts the dynamic range in the Raw image so that the photographer can make a more informed decision about what if anything to *subsequently* do to the exposure. Everybody can see it except you and that is the only claim that has been made for it (except by you).

Floyd is arguing with the demons in his head (and losing).
Is there anything else left to discuss amongst the rest of us?

Another article from Wibla with *nothing* but gratuitous insults.

But what purpose is there in hurling insults at someone
just because you are unable to understand the topic well enough to digest technical discussion about it? You’ve
demonstrated that you can’t even measure the difference
between the so called headroom of RAW data over JPEG,
yet you want to argue the fine points of histogram
accuracy???? That is an absurd contradiction.

Neither you nor DRS were even able to analyze a couple of fairly simple histograms; so just were *do* you get off
with these insults?

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Chris Malcolm

Oct 11, 2009

In rec.photo.digital.slr-systems Paul Furman wrote:

What about saturation? Reducing saturation seems to give more detail to the edges also.

That could be a side effect of chromatic aberration. Do you notice it when there’s no chromatic aberration?

—
Chris Malcolm

john

Oct 11, 2009

On Fri, 09 Oct 2009 16:05:56 -0500, Hilarity Ensues
wrote:

On Fri, 09 Oct 2009 10:44:52 -0800, (Floyd L. Davidson) wrote:

And do note that later today I’ll post an extensive analysis of each, showing exactly what can be understood from them.

Oh, this is going to be good. Let me go get some popcorn, and a milkshake. So when I laugh real hard the milkshake will come streaming out of my nose.

Try not to choke on your tater tots.

john

Oct 11, 2009

On 11 Oct 2009 09:59:27 GMT, Chris Malcolm
wrote:

In rec.photo.digital.slr-systems Paul Furman wrote:

What about saturation? Reducing saturation seems to give more detail to the edges also.

That could be a side effect of chromatic aberration. Do you notice it when there’s no chromatic aberration?

Or from chroma subsampling if you’re working with jpegs.

Porte Rouge

Oct 11, 2009

On Oct 10, 3:30 am, (Floyd L. Davidson) wrote:

sigh… wrote:

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Setting White Balance will have a dramatic effect of the accuracy of both.

Could you tell me how you go about setting the white balance on your camera? I read this page:

http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm

The first method is over my head and I have a Nikon that doesn’t use saturated pixels for the calculation of white balance. My white balance can be set to Auto(+ or – 3), by lighting(tungsten, fluorescent, flash), outside light (direct sun, shade, cloudy), select a temperature, and presets(measure a gray card or use WB from another photo). Which would you recommend?

Porte

floyd

Oct 11, 2009

Porte Rouge wrote:

On Oct 10, 3:30 am, (Floyd L. Davidson) wrote:

sigh… wrote:

On Thu, 08 Oct 2009 18:36:37 -0800, (Floyd L. Davidson) wrote:

Setting White Balance will have a dramatic effect of the accuracy of both.

Could you tell me how you go about setting the white balance on your camera? I read this page:

http://www.guillermoluijk.com/tutorial/uniwb/index_en.htm
The first method is over my head and I have a Nikon that doesn’t use saturated pixels for the calculation of white balance. My white balance can be set to Auto(+ or – 3), by lighting(tungsten, fluorescent, flash), outside light (direct sun, shade, cloudy), select a temperature, and presets(measure a gray card or use WB from another photo). Which would you recommend?

I use Nikon cameras and shoot RAW+JPEG virtually all of
the time, using the JPEG for preview only and process
RAW files for production. The JPEG is often enough
previewed using the camera’s LCD (I show somebody a shot that was just made, or even let them scroll through
several images), but is usually seen via a laptop LCD.
Hence a realistic JPEG is important, but does not need
to be perfect.

Also, I use the histogram as a rough indicator of
exposure, and the "highlight" display to actually decide if an image was exposed correctly.

I always use "Auto" for White Balance. The significant effect of doing so, for my workflow, is that the camera
records whatever multipliers were used. If a preset WB
setting is used, the preset multipliers are recorded,
but we already know what those values are so recording
them is not useful (they are also used as preset values by the raw converter). By using "Auto" I get a record of what the camera thought WB should be.

When I process the RAW file (I use UFRAW) I can use the
camera generated auto values or I can use what the
program’s "auto" setting generates. Sometimes they are very similar, sometimes not, but usually one or the
other is close enough to what I want to provide a
starting point for manual adjustment of the program’s
White Balance.

I have tried the UniWB concept, and it certainly works
as described. It was nice to have a very accurate JPEG
in terms of the histogram’s indication of exposure,
but… I can’t live with the greenish looking JPEGs
produced. 🙂 I can live with knowing that to nail
exposure I need to allow at least some portion of the
image to blink in the highlight display. I just keep in mind that getting more dynamic range means a little more area blinking, and positively avoiding clipped
highlights means a little less. It’s a judgement call
that depends on circumstances, and in any case is never
very critical.

A lot of folks say what they want is an histogram
generated directly from the camera’s raw data.
Un-interpolated raw data histograms aren’t very useful
though! What I would like to see is the camera do one
interpolation for the JPEG image and an entirely
separate interpolation for a histogram. For those who
shoot JPEG, the settings would be the same (or just use
the JPEG for the histogram as is now done). For those
who shoot RAW the interpolation could be set for using
1.0 multipliers, low saturation, no sharpening, and
a standard gamma, to get a very accurate histogram.

I wouldn’t mind seeing an "expanded" histogram display either, where the entire graph shows only the upper 2
fstops of the histogram and also truncates the vertical
range by 1/2. What a tool that would be!

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Bob Larter

Oct 12, 2009

Paul Furman wrote:

OK, this makes sense, the posterizing issue is not really visible in any sort of normal exposure. What about Floyd’s comment below that the noise level remains the same but exposing to the right increases the signal so that overwhelms the noise? That seems to tie the two together in a comprehensible way.

Look at it this way: Your RAW image will have the same amount of noise, regardless of the exposure. But exposing to the right will lift the shadow levels up higher, relative to the noise. When you process the RAW image on your PC, you’ll lower the brightness levels back down, thus lowering the absolute noise levels with them.
More technically, you’re maximising the signal-to-noise ratio.

—
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est —^—-^————————————————— ————

Alan Browne

Oct 12, 2009

DRS wrote:

"Alan Browne" wrote in message

sigh… wrote:

[…]

Nothing can be determined from either without the accompanying photograph.

BS. It’s clear that the first one was mostly shadow, probably a black card (or underexposed grey card). There may have been a shiny patch, or perhaps a white edge to explain the bumps on the right…

It was a night shot landscape with a blue cast. The moon provide the smattering of pixels on the right.

The second a white card (or over exposed grey card).

It was a snow-laden tree surrounded by snow. The image had a hint of fog. All those whites and light grays predictably pushed everything over to the right.

This is so easy to replicate…

True. And it also manages to avoid the point (not you, Floyd).

For nothing more than confirmation I just replicated the same results as in the links (minus the white over grey point) using an old grey card. Any adjustment of flash output, aperture or ISO generated the same results (although a narrower histo than in the links).

No surprise. I could have added a small white disk to the grey card to get the additional data to the right (emulate the "moon" in dark sky image).

Same could be done with a white card or black card.

Paul Furman

Oct 12, 2009

John A. wrote:

On 11 Oct 2009 09:59:27 GMT, Chris Malcolm
wrote:

In rec.photo.digital.slr-systems Paul Furman wrote:

What about saturation? Reducing saturation seems to give more detail to the edges also.

That could be a side effect of chromatic aberration. Do you notice it when there’s no chromatic aberration?

Or from chroma subsampling if you’re working with jpegs.

I don’t think either would have much effect. It looks to make as big of a difference as contrast.

—
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

Porte Rouge

Oct 13, 2009

So, with WB all set you take a picture. I gather that you expose to the right? My sunrise is good example of lighting conditions that lead to especially washed out colors if you do. How do you adjust the colors in post or do you just meter for the sunrise and let the histogram fall where it may. When I shot slide film I would spot meter on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

Porte

floyd

Oct 14, 2009

Porte Rouge wrote:

So, with WB all set you take a picture. I gather that you expose to the right? My sunrise is good example of lighting conditions that lead to especially washed out colors if you do. How do you adjust the colors in post or do you just meter for the sunrise and let the histogram fall where it may.

If you don’t want any part of the scene to clip, then
shoot the sunrize ETTR. It is *absolutely* necessary to post process, where you set the exposure for whatever
effect you like. ETTR does *not* cause washed out
colors (inappropriate post processing might though).

When I shot slide film I would spot meter
on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

How can you spot meter on an area that "I knew what the meter would read"??? I don’t understand what you mean by that statement.

If the histogram is not as far to the right as it could
be your image does not have as wide a dynamic range as
the camera is capable of recording. The shadow areas
will have more noise than if it were exposed per ETTR.
If you want any specific *final* tone levels, set it
that way in post processing. In essence, in post
processing drop the "exposure" to make the editor’s histogram show what you think the camera’s should have
shown absent ETTR adjustments.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Steven Redgate

Oct 14, 2009

If you don’t want any part of the scene to clip, then
shoot the sunrize ETTR.  It is *absolutely* necessary to post process, where you set the exposure for whatever
effect you like.  ETTR does *not* cause washed out
colors (inappropriate post processing might though).

By "washed out" I mean the image is brighter than what I saw when I took the picture and to get the image to represent what I saw I need to darken the image. By either reducing exposure or some other method in post.

When I shot slide film I would spot meter
on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

How can you spot meter on an area that "I knew what the meter would read"???  I don’t understand what you mean by that statement.

I spot meter on something that, from experience, I know what I want the light meter to indicate for exposure. For example (for film, no ETTR), a gray cloud I set exposure so the meter reads in the middle of the exposure display, a white cloud plus 1 or 2 stops, a black cloud minus 1 or 2 stops.

If the histogram is not as far to the right as it could
be your image does not have as wide a dynamic range as
the camera is capable of recording.  The shadow areas
will have more noise than if it were exposed per ETTR.
If you want any specific *final* tone levels, set it
that way in post processing.  In essence, in post
processing drop the "exposure" to make the editor’s histogram show what you think the camera’s should have
shown absent ETTR adjustments.

Do you specifically reduce the exposure in post or some other method? There are exposure sliders in ACR and Lightroom, as well as CS4.

Porte

floyd

Oct 14, 2009

Steven Redgate wrote:

If you don’t want any part of the scene to clip, then
shoot the sunrize ETTR.  It is *absolutely* necessary to post process, where you set the exposure for whatever
effect you like.  ETTR does *not* cause washed out
colors (inappropriate post processing might though).

By "washed out" I mean the image is brighter than what I saw when I took the picture and to get the image to represent what I saw I need to darken the image. By either reducing exposure or some other method in post.

You are aware that ETTR is a two part process, part one
being boost the exposure to maximum possible, and part
two is to later reduce it to whatever it is that makes
your heart beat fast enough.

You *have* to do both.

When I shot slide film I would spot meter
on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

How can you spot meter on an area that "I knew what the meter would read"???  I don’t understand what you mean by that statement.

I spot meter on something that, from experience, I know what I want the light meter to indicate for exposure. For example (for film, no ETTR), a gray cloud I set exposure so the meter reads in the middle of the exposure display, a white cloud plus 1 or 2 stops, a black cloud minus 1 or 2 stops.

So you take wild guesses at what shade various parts of the scene are! (Isn’t the whole idea of a meter supposed to be to get away from these wild guesses about exposure??? 🙂

Sarcasm aside (because certainly with film that was an
almost required method), you don’t need to guess any
more. Digital cameras provide tools that will
positively show you where your image is in terms of the
camera’s dynamic range capability. That’s what a
histogram does.

If the histogram is not as far to the right as it could
be your image does not have as wide a dynamic range as
the camera is capable of recording.  The shadow areas
will have more noise than if it were exposed per ETTR.
If you want any specific *final* tone levels, set it
that way in post processing.  In essence, in post
processing drop the "exposure" to make the editor’s histogram show what you think the camera’s should have
shown absent ETTR adjustments.

Do you specifically reduce the exposure in post or some other method? There are exposure sliders in ACR and Lightroom, as well as CS4.

Yes, in post processing.

In the camera, try to set exposure as high as is
possible. The closer to clipping the better (indeed,
clipping of some types of highlights might be perfectly
okay). The camera is essentially going to record the
same amount of noise regardless of your exposure
settings, so increasing exposure increases the
Signal-To-Noise-Ratio.

In post processing reduce exposure (which reduces noise
at the same amount it does the highlights) to give the
desired brightness.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Bob Larter

Oct 14, 2009

Steven Redgate wrote:

If you don’t want any part of the scene to clip, then
shoot the sunrize ETTR. It is *absolutely* necessary to post process, where you set the exposure for whatever
effect you like. ETTR does *not* cause washed out
colors (inappropriate post processing might though).

By "washed out" I mean the image is brighter than what I saw when I took the picture and to get the image to represent what I saw I need to darken the image. By either reducing exposure or some other method in post.

Correct. You can reduce the exposure slider, or you can move the black level on the tone curve to the left hand side of the histogram (which is what I do), which retains the highlights.

—
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est —^—-^————————————————— ————

Porte Rouge

Oct 14, 2009

You are aware that ETTR is a two part process, part one
being boost the exposure to maximum possible, and part
two is to later reduce it to whatever it is that makes
your heart beat fast enough.

You *have* to do both.

Yes, I understand. My question is, after ETTR what exactly do you yourself do in post processing. Do you adjust exposure, black point, or something else?

When I shot slide film I would spot meter
on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

How can you spot meter on an area that "I knew what the meter would read"???  I don’t understand what you mean by that statement.

I spot meter on something that, from experience, I know what I want the light meter to indicate for exposure. For example (for film, no ETTR), a gray cloud I set exposure so the meter reads in the middle of the exposure display, a white cloud plus 1 or 2 stops, a black cloud minus 1 or 2 stops.

So you take wild guesses at what shade various parts of the scene are!  (Isn’t the whole idea of a meter supposed to be to get away from these wild guesses about exposure??? 🙂

It’s not really a wild guess. It’s like the earlier post about the snow bank. I was taught and learned that if I spot metered the snow and set exposure so the exposure display read dead center, the snow would be gray in the photo. If I use 1 or 2 stops more exposure it will be whiter. If I spot meter the black dog and the exposure meter is centered the dog will be gray, so I use less exposure and it will be darker.

Porte

floyd

Oct 14, 2009

Porte Rouge wrote:

You are aware that ETTR is a two part process, part one
being boost the exposure to maximum possible, and part
two is to later reduce it to whatever it is that makes
your heart beat fast enough.

You *have* to do both.

Yes, I understand. My question is, after ETTR what exactly do you yourself do in post processing. Do you adjust exposure, black point, or something else?

"After ETTR" means it follows adjusting *exposure* in post processing.

Incidentally, black point has nothing to do with ETTR or exposure. For most images if gamma is set correctly
there is no need to move the black point up. Generally
I click on "Auto" for black point, and if it moves the curve away from the lower right corner I reset it and
review the gamma settings to make sure I’ve got that
right. Some times it does work out that it helps to
move the black point, but not often.

I adjust exposure, white balance, gamma and linearity,
black point, color saturation and potentially things
like noise reduction and certain lens specific
corrections all with the raw converter. An image editor is used for resizing, cropping, retouching, USM, borders, watermarks, etc.

When I shot slide film I would spot meter
on an area that I knew what the meter should read and set exposure accordingly, and in digital this also yields a good looking sunrise. The histogram, however, is not as far to the right as it could be.

How can you spot meter on an area that "I knew what the meter would read"???  I don’t understand what you mean by that statement.

I spot meter on something that, from experience, I know what I want the light meter to indicate for exposure. For example (for film, no ETTR), a gray cloud I set exposure so the meter reads in the middle of the exposure display, a white cloud plus 1 or 2 stops, a black cloud minus 1 or 2 stops.

So you take wild guesses at what shade various parts of the scene are!  (Isn’t the whole idea of a meter supposed to be to get away from these wild guesses about exposure??? 🙂

It’s not really a wild guess. It’s like the earlier post about the snow bank. I was taught and learned that if I spot metered the snow and set exposure so the exposure display read dead center, the snow would be gray in the photo. If I use 1 or 2 stops more exposure it will be whiter.

So you take a wild guess at 1 or 2 stops more! Even
with film and no histograms most accomplished
photographers attempted to get within 1/2 a stop.
Today, with digital and histograms, it is entirely
possible to be within 1/3rd of a stop.

This may or may not be obvious (I live 300+ miles north
of the Arctic Circle); but do realize that I literally
take thousands of images that include snow! It really
does require paying attention before hand if you want
detail in the snow, or if it can just be "white" or if it can be blown out totally. (There is this
false claim that Eskimos have 100 words for snow, which
they don’t… but skiers do and so do photographers! 🙂

And all of that has to be balanced against the
brightness level for people’s faces, black dogs, and
white bears.

If I spot meter the black dog and the exposure meter
is centered the dog will be gray, so I use less exposure and it will be darker.

You guess at how much darker it should be…

What a spot meter can show you (and a histogram can show even more easily), is how much of a range you have
between the dog and whatever else there is. If it
happens to be a snow bank, it might well be 7 or 8 stops difference and arbitarily adjusting the dog to something that "will be darker" will mean that you lose the texture of the snow. The trick is realizing that the
dog is going to be off scale, so getting texture on both the snow and the dog means putting the snow right at the maximum. Then in post processing the brightness is
adjusted to maintain the snow at just under maximum
white while contrast is adjusted to bring the texture on the dog out of the black.

It depends on the dynamic range of your camera of
course, but the closer one puts the snow to maximum
white the less noise will show up on the texture of the
dog.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Porte Rouge

Oct 14, 2009

So you take a wild guess at 1 or 2 stops more!  Even
with film and no histograms most accomplished
photographers attempted to get within 1/2 a stop.
Today, with digital and histograms, it is entirely
possible to be within 1/3rd of a stop.

Floyd, baby, chill out. "Wild guess" is over the top. I’m a slow typer, I didn’t go into a lot of detail about the metering. I do all the stuff in your post here, meter, histogram, Photoshop, ACR (thanks for the link to UFRAW by the way,that looks interesting) I was just checking to see what other methods people used to correct their photos in post processing.

This may or may not be obvious (I live 300+ miles north
of the Arctic Circle); but do realize that I literally
take thousands of images that include snow!  It really
does require paying attention before hand if you want
detail in the snow, or if it can just be "white" or if it can be blown out totally.  (There is this
false claim that Eskimos have 100 words for snow, which
they don’t… but skiers do and so do photographers! 🙂
And all of that has to be balanced against the
brightness level for people’s faces, black dogs, and
white bears.

If I spot meter the black dog and the exposure meter
is centered the dog will be gray, so I use less exposure and it will be darker.

You guess at how much darker it should be…

What a spot meter can show you (and a histogram can show even more easily), is how much of a range you have
between the dog and whatever else there is.  If it
happens to be a snow bank, it might well be 7 or 8 stops difference and arbitarily adjusting the dog to something that "will be darker" will mean that you lose the texture of the snow.  The trick is realizing that the
dog is going to be off scale, so getting texture on both the snow and the dog means putting the snow right at the maximum.  Then in post processing the brightness is
adjusted to maintain the snow at just under maximum
white while contrast is adjusted to bring the texture on the dog out of the black.

It depends on the dynamic range of your camera of
course, but the closer one puts the snow to maximum
white the less noise will show up on the texture of the
dog.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)              

floyd

Oct 15, 2009

Porte Rouge wrote:

So you take a wild guess at 1 or 2 stops more!  Even
with film and no histograms most accomplished
photographers attempted to get within 1/2 a stop.
Today, with digital and histograms, it is entirely
possible to be within 1/3rd of a stop.

Floyd, baby, chill out. "Wild guess" is over the top. I’m a slow

It’s a wild guess.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)

Bob Larter

Oct 15, 2009

Porte Rouge wrote:

You are aware that ETTR is a two part process, part one
being boost the exposure to maximum possible, and part
two is to later reduce it to whatever it is that makes
your heart beat fast enough.

You *have* to do both.

Yes, I understand. My question is, after ETTR what exactly do you yourself do in post processing. Do you adjust exposure, black point, or something else?

I adjust black point, which retains the highlights.

—
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est —^—-^————————————————— ————

Porte Rouge

Oct 15, 2009

On Oct 14, 11:56 pm, (Floyd L. Davidson) wrote:

Porte Rouge wrote:

So you take a wild guess at 1 or 2 stops more!  Even
with film and no histograms most accomplished
photographers attempted to get within 1/2 a stop.
Today, with digital and histograms, it is entirely
possible to be within 1/3rd of a stop.

Floyd, baby, chill out. "Wild guess" is over the top. I’m a slow

It’s a wild guess.

—
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson> Ukpeagvik (Barrow, Alaska)              

Oh, well, that’s too bad. I guess that’s as far as we go, Floyd. Thanks for answering my questions.

Porte

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