Photoshop and Huey: Double color correction?

On Sun, 13 Apr 2008 18:30:20 -0700 (PDT), André Hänsel wrote:

Hi,

I am using a Pantone Huey Pro for color correcting my monitor. Basically it does two things: It adds a profile to the monitor and the Software does a color correction (probably with the aid of the graphics card).

Now Photoshop (CS2) does also use the monitor profile for color correction.

Isn’t the image over-corrected by applying it twice?

There is no double conversion. The Huey software calibrates the monitor, using the LUT in the video card, then creates a profile that describes the monitor. Then Photoshop uses the monitor profile oin the intended way: to convert color numbers for display.
—
Mike Russell – http://www.curvemeister.com

André Hänsel wrote:

Hi,

I am using a Pantone Huey Pro for color correcting my monitor. Basically it does two things: It adds a profile to the monitor and the Software does a color correction (probably with the aid of the graphics card).

Now Photoshop (CS2) does also use the monitor profile for color correction.

Isn’t the image over-corrected by applying it twice?

I don’t know what in your mind by doubling your confusion <bg> but this is how the whole thing works in general.

– The Monitor Calibrator calculates the Monitor base on the lighting situation of your work station.

– It then give the option to SAVE the Monitor Profile to computer (Windows for example as I am not Mac user to know anything about it), and tell Windows to use that specific Monitor Profile as the DEFALT.

Yes, you can choose other monitor profile’s if you wish, and Windows may have more/less profile files (probably depending on what you have installed on your system?)

– Then just like all applications using Monitor Profile, Photoshop will use the DEFAULT (the one created and saved by Pantone Huey Pro) monitor profile as its default monitor profile.

That’s it! other than that I have no idea what the "TWO" and "TWICE" you have in

Regards,
André

On Apr 14, 7:19 am, Mike Russell
wrote:

On Sun, 13 Apr 2008 18:30:20 -0700 (PDT), André Hänsel wrote:

Hi,

I am using a Pantone Huey Pro for color correcting my monitor. Basically it does two things: It adds a profile to the monitor and the Software does a color correction (probably with the aid of the graphics card).

Now Photoshop (CS2) does also use the monitor profile for color correction.

Isn’t the image over-corrected by applying it twice?

There is no double conversion. The Huey software calibrates the monitor, using the LUT in the video card, then creates a profile that describes the monitor. Then Photoshop uses the monitor profile oin the intended way: to convert color numbers for display.

Hm, I’m not sure whether I understand. Let me wrap it in an example: In Photoshop I create a picture using a color, e.g. 10% red, 20% green, 30% blue. When I create a screenshot now and measure the color it is 19 R, 26 G, 35 B, because of the screen profile. When I now turn Huey color correction on, the color I see on the screen changes. So if this is the "correct" color, what is the color I saw when color correction was still off? Half corrected?

On Sun, 18 May 2008 16:54:43 -0700 (PDT), André Hänsel wrote:

On Apr 14, 7:19 am, Mike Russell
wrote:

On Sun, 13 Apr 2008 18:30:20 -0700 (PDT), André Hänsel wrote:

Hi,

I am using a Pantone Huey Pro for color correcting my monitor. Basically it does two things: It adds a profile to the monitor and the Software does a color correction (probably with the aid of the graphics card).

Now Photoshop (CS2) does also use the monitor profile for color correction.

Isn’t the image over-corrected by applying it twice?

There is no double conversion. The Huey software calibrates the monitor, using the LUT in the video card, then creates a profile that describes the monitor. Then Photoshop uses the monitor profile oin the intended way: to convert color numbers for display.

Hm, I’m not sure whether I understand. Let me wrap it in an example: In Photoshop I create a picture using a color, e.g. 10% red, 20% green, 30% blue. When I create a screenshot now and measure the color it is 19 R, 26 G, 35 B, because of the screen profile. When I now turn Huey color correction on, the color I see on the screen changes. So if this is the "correct" color, what is the color I saw when color correction was still off? Half corrected?

More than likely this is the interraction of the color profile, which Photoshop recognizes, and the video card’s look up table (LUT), which directly changes the appearance of the RGB values.

The exact explanation of your example is difficult to give for several reasons. YYou don’t mention which software you are using to turn on the Huey color correction, and the interpretation of color values that are pasted into Photoshop depends on your profile mismatch settings in Color Setup. To preserve their appearance, screen shots should always be first assigned the display profile, then converted to your working color space. —
Mike Russell – http://www.curvemeister.com

"Andr

On May 19, 4:17 am, Mike Russell
wrote:

On Sun, 18 May 2008 16:54:43 -0700 (PDT), André Hänsel wrote:

On Apr 14, 7:19 am, Mike Russell
wrote:

On Sun, 13 Apr 2008 18:30:20 -0700 (PDT), André Hänsel wrote:

Hi,

I am using a Pantone Huey Pro for color correcting my monitor. Basically it does two things: It adds a profile to the monitor and the Software does a color correction (probably with the aid of the graphics card).

Now Photoshop (CS2) does also use the monitor profile for color correction.

Isn’t the image over-corrected by applying it twice?

There is no double conversion. The Huey software calibrates the monitor, using the LUT in the video card, then creates a profile that describes the monitor. Then Photoshop uses the monitor profile oin the intended way: to convert color numbers for display.

Hm, I’m not sure whether I understand. Let me wrap it in an example: In Photoshop I create a picture using a color, e.g. 10% red, 20% green, 30% blue. When I create a screenshot now and measure the color it is 19 R, 26 G, 35 B, because of the screen profile. When I now turn Huey color correction on, the color I see on the screen changes. So if this is the "correct" color, what is the color I saw when color correction was still off? Half corrected?

More than likely this is the interraction of the color profile, which Photoshop recognizes, and the video card’s look up table (LUT), which directly changes the appearance of the RGB values.

The exact explanation of your example is difficult to give for several reasons. YYou don’t mention which software you are using to turn on the Huey color correction, and the interpretation of color values that are pasted into Photoshop depends on your profile mismatch settings in Color Setup. To preserve their appearance, screen shots should always be first assigned the display profile, then converted to your working color space.

To turn on the Huey color correction I use the Huey Software where I can switch from "Uncorrected" to "Corrected" which changes the appearance of colors immediately.

Indeed when I take a screenshot of a picture that is in the color profile of my monitor (and not sRGB as before) the measured colors are the same, regardless of what color profile the image has that I paste into.
Nevertheless could you explain what happens when I screenshot an sRGB image and leave Huey color correction turned off? By the way, when I remove the screen profile in system control and then screenshot an sRGB image I have consistent (but probably visibly wrong) colors.

On Mon, 19 May 2008 08:20:12 -0700 (PDT), André Hänsel wrote:

[re monitor correction]

To turn on the Huey color correction I use the Huey Software where I can switch from "Uncorrected" to "Corrected" which changes the appearance of colors immediately.

If it works the same as the i1, this is changing the video card’s lookup table (LUT) that was created by the Huey, but leaving the system display profile in place. Since the video LUT modifies the hardware settings, it is like a high tide raising all boats equally, changing the colors displayed by all apps, whether they are color aware or not.

Indeed when I take a screenshot of a picture that is in the color profile of my monitor (and not sRGB as before) the measured colors are the same, regardless of what color profile the image has that I paste into.

Photoshop copies the RGB values directly from the clipboard into the image. This will change the color appearance because Photoshop now believes that these RGB values belong to the image’s working space defined by the image’s working color profile, and uses the display profile to convert those colors from the image’s color space to the display space, defined by the display profile.

Nevertheless could you explain what happens when I screenshot an sRGB image and leave Huey color correction turned off?

Photoshop converts your sRGB colors to display space. When you do the screenshot, you copy display space RGB values to the clipboard. Pasting them back into the sRGB image will put these converted color values back into the sRGB image space, and they will probably appear slightly different at that point.

Since the Huey LUT is missing, this will alter the display appearance only. It does not change the RGB numbers.

By the way, when I remove the screen profile in system control and then screenshot an sRGB image I have consistent (but probably visibly wrong) colors.

Photoshop uses a default screen space of sRGB if none is specified in the display properties. SRGB was designed to match the average monitor, so it’s not surprising that it matches your display fairly well.

Other thigs that color wonks might find interesting:

In the advanced section of Color Settings, there are several options for dealing with profile mismatches. For opening an image file, there is a profile mismatch option to "Ask when Opening for images with both mismatched profiles missing profiles. There is an option for displaying a warning when a pasted image is tagged with a different profile, but the missing profile option is not available for pasting. This means that it is not possible to get a warning when pasting an image from a screenshot – the pixel values are silently assigned whatever your working profile is.

It is easier to see how things work if you use a more extreme profile, such as Wide Gamut RGB or ProPhoto RGB. The increase in saturation with these profiles is so obvious that you will see whether colors are being changed, and whether they are being displayed correctly or not. The numbers also change more with these profiles. You can create your own pseudo profiles with various gamma values, and see if you can predict things like whether pasting a middle gray from a 1.0 gamma image to a 2.3 gamma image will make the image darker or lighter.

You mentioned the notion of "accurate colors". I’ve posted another thread on the topic of "calibrationism vs by the numbers" that you may find interesting.

—
Mike Russell – http://www.curvemeister.com

On May 20, 7:36 am, Mike Russell
wrote:

On Mon, 19 May 2008 08:20:12 -0700 (PDT), André Hänsel wrote:
[re monitor correction]

To turn on the Huey color correction I use the Huey Software where I can switch from "Uncorrected" to "Corrected" which changes the appearance of colors immediately.

If it works the same as the i1, this is changing the video card’s lookup table (LUT) that was created by the Huey, but leaving the system display profile in place. Since the video LUT modifies the hardware settings, it is like a high tide raising all boats equally, changing the colors displayed by all apps, whether they are color aware or not.

Indeed when I take a screenshot of a picture that is in the color profile of my monitor (and not sRGB as before) the measured colors are the same, regardless of what color profile the image has that I paste into.

Photoshop copies the RGB values directly from the clipboard into the image.. This will change the color appearance because Photoshop now believes that these RGB values belong to the image’s working space defined by the image’s working color profile, and uses the display profile to convert those colors from the image’s color space to the display space, defined by the display profile.

Nevertheless could you explain what happens when I screenshot an sRGB image and leave Huey color correction turned off?

Photoshop converts your sRGB colors to display space. When you do the screenshot, you copy display space RGB values to the clipboard. Pasting them back into the sRGB image will put these converted color values back into the sRGB image space, and they will probably appear slightly different at that point.

This is a very good explanation of what happens when I take the screenshot, thanks.

Since the Huey LUT is missing, this will alter the display appearance only.. It does not change the RGBnumbers.

I’m not sure if I understood this, because my original question remains, but rephrased:
When I open an image that is in sRGB (or even a more extreme profile) Photoshop tries to find similar colors in my display’s profile to achieve that I see the image as genuine as possible, correct? So when I now turn on the Huey color correction, I void Photoshop’s effort.

Or does the Huey color correction serve the purpose of "correcting" color unaware applications and the Huey-created display profile describes the already corrected display so that color aware applications can target the RGB values to this color space? (Which answers my question whether the image in Photshop is "half corrected" when Huey is off with "yes".)

It is easier to see how things work if you use a more extreme profile, such as Wide Gamut RGB or ProPhoto RGB. The increase in saturation with these profiles is so obvious that you will see whether colors are being changed, and whether they are being displayed correctly or not. Thenumbersalso change more with these profiles. You can create your own pseudo profiles with various gamma values, and see if you can predict things like whether pasting a middle gray from a 1.0 gamma image to a 2.3 gamma image will make the image darker or lighter.

Well, I predict that it will be darker, because when I paste pixel color values from the gamma 1 ("not gamma compressed" so to speak) to the gamma 2.3 image, the system will think they were gamma compressed (lightened) by 2.3 in the first place, so it will darken them before output.

You mentioned the notion of "accurate colors". I’ve posted another thread on the topic of "calibrationismvsby thenumbers" that you may find interesting.

Yes, basically you’re right but I hoped, with the aid of the Huey I could estimate better what I’ll get from the lab by looking on my screen.

On Tue, 20 May 2008 19:15:20 -0700 (PDT), André Hänsel wrote:

….

I’m not sure if I understood this, because my original question remains, but rephrased:
When I open an image that is in sRGB (or even a more extreme profile) Photoshop tries to find similar colors in my display’s profile to achieve that I see the image as genuine as possible, correct? So when I now turn on the Huey color correction, I void Photoshop’s effort.

Yes, when you turn the LUT on and off, the appearance of the image changes, but not the screen grab numbers.

Or does the Huey color correction serve the purpose of "correcting" color unaware applications and the Huey-created display profile describes the already corrected display so that color aware applications can target the RGB values to this color space? (Which answers my question whether the image in Photshop is "half corrected" when Huey is off with "yes".)

You got it. The Huey LUT tunes in an appropriate gamma and color temp, based on what you specified. This is not a complete specification of the monitor appearance. The profile adds the finishing touches, and includes things like the purity of the monitor’s red, green, and blue.

….
[re pasting gamma 1 colors into a gamma 2.2 image]

Well, I predict that it will be darker, because when I paste pixel color values from the gamma 1 ("not gamma compressed" so to speak) to the gamma 2.3 image, the system will think they were gamma compressed (lightened) by 2.3 in the first place, so it will darken them before output.

Easy to verify. Here’s another brain twister: if you assign Wide Gamut RGB as your system’s display profile, do the colors get more or less intense?

[re accurate colors]

Yes, basically you’re right but I hoped, with the aid of the Huey I could estimate better what I’ll get from the lab by looking on my screen.

This is probably the case. Screen calibrators are relatively inexpensive now, and work reasonably well. It also works to put a representative image on your screen, and adjust the controls to make it look right. —
Mike Russell – http://www.curvemeister.com