transforming images rgb to cmyk

MR
Posted By
Mike Russell
May 24, 2005
Views
600
Replies
18
Status
Closed
wrote:
[re conversion of RGB to CMYK]
By "Certain colors can not be reproduced in CMYK", I assume you meant out of gamut colors between color spaces. But some colors on a monitor that are not flagged as oog in PS still won’t show up in Epson inkjet prints, after all the fuzz of monitor calibration and custom printer profiles. Is the PS oog detection faulty? Aside from oog detection, are there other ways to find out what colors won’t print?

There are a host of technical issues with out of gamut colors. The ICC standard defines a "tag" that defines out of gamut colors.

But the gamut tag is not always included in a profile, and when it is, it is not used consistently by different manufacturers. So programs like Photoshop generally ignore the gamut tag, perferring instead to rely on color values calculated using the profile. One rather simple method of doing this is to see if converting the color back and forth gives the same result. For example, converting the out of gamut RGB (255,0,0) into CMYK and back again gives a different RGB value from the original (RGB(199,3,3), say). When this happens, that particular color is considered out of gamut.

There are other, better, ways to calculate out of gamut colors, and I suspect the Photoshop engine uses one of those. BTW, out of gamut colors are calculated by the engine, not by Photoshop itself. You can experiment by telling Photoshop to use the Microsoft (or Apple) ICM engine in your color prefs.

But this only says that the profile generates unique values for a particular color, and not whether the printer itself yields a different color when that color and colors close to it in value are printed. Given the limits of the current technology, particularly the poor support of the gamut tag, the only way to tell for sure is to print the colors, and scan them with a photometer or spectrophotometer. You can’t even look at the darn things to tell if they are different, because the differences are very subtle. No wonder there is so much confusion, so much being spent on calibration equipment, and relatively little result to show for it.

But most of us realize that our inkjet printers do a pretty good job. If printers were watches, at this time in history they would accurate to a couple of minutes a day. As was the case with watches, there are those who require (or think that they require) greater accuracy, and are willing to pay for it. As has happened already with watches, at some point in the future printers will probably be extremely accurate and inexpensive. Until that happens, most of us can easily live comfortably with less than perfection.

Here are some more thoughts that I hope will give pause to some of you who have bought into the conventional wisdom that larger gamuts are always better than smaller ones.

1) What was the last out of gamut object you photographed? Blue sky, for example, is not really that saturated, particularly near the horizon where most of our cameras are pointed. Red objects – even bright bird plumage, is a far cry from RGB(255,0,0). For most of us, the answer to the question is "none".

2) RGB is not the last word in color spaces. Consider pure yellow objects, which are not all that uncommon, are not at all well represented in the RGB color space. For most monitors RGB(255,255,0) is brighter, but less saturated, than CMYK(0,0,100,0) will be in print. Magenta and cyan objects have similar problems.

Recent monitor developments have made an end run around this problem, resulting in the apparent miracle of a monitor capable of displaying the Adobe RGB color space directly. This is achieved by filtering the RGB phosphors to create purer colors, sharpening and stretching the three corners of the RGB gamut (to see these shapes, check out Curvemeister’s Labmeter, a free gamut plotter image). But even purity can have its limits, and the extermely sharp spectral characteristics of these monitors are bringing a new problem, viewer metamerism, to the forefront. With this latest advance, color consistency is literally in the eye of the beholder. The color on these monitors simply look funny to some people.

3) Consider that a larger gamut such as Adobe RGB sacrifices color gradation. An Adobe RGB image uses a smaller number of color values to represent the same range of colors than an sRGB image. This issue may be addressed by working in 16 bits, but there is a more serious problem to working in a large gamut space: the high probability that someone else may look at your image on an sRGB monitor and conclude that your work is too drab. Both of these issues – particularly the second one – are reasons for working in sRGB, particularly since real world objects such as pure blue sky do not come close to exceeding the gamut of even sRGB.

4) Print has a much smaller gamut than a CRT. The big money in photography is still in printed images, whether they be published images, or wall-sized art.

My suggestion, as always, is to trust what you can see and verify, and not spend too much time or money on getting your "watch" to run within one second of correct. Todays color and printer technology is excellent, and most of us – the vase majority – can live with its imperfections, provided we understand them, and base our understanding on common sense. —

Mike Russell
www.curvemeister.com

How to Improve Photoshop Performance

Learn how to optimize Photoshop for maximum speed, troubleshoot common issues, and keep your projects organized so that you can work faster than ever before!

T
Tacit
May 25, 2005
In article , wrote:

By "Certain colors can not be reproduced in CMYK", I assume you meant out of gamut colors between color spaces.

Yes, that’s correct. For example, pure RGB blue ain’t never going to be reproduced in CMYK.

But some colors on a monitor
that are not flagged as oog in PS still won’t show up in Epson inkjet prints, after all the fuzz of monitor calibration and custom printer profiles. Is the PS oog detection faulty? Aside from oog detection, are there other ways to find out what colors won’t print?

Photoshop’s out of gamut detection is remarkably good; however, there are many issues which may confound trying to identify out of gamut colors on an inkjet print.

For starters, Photoshop’s out of gamut detection uses the current CMYK setup; if this is incorrect (for example, if you’re using a SWOP profile, intended for printing presses, rather than a profile for your inkjet printer), Photoshop will show you the colors out of gamut for a printing press, not your printer.

Second, when you print CMYK to an inkjet printer, the printer’s drive software converts from CMYK to RGB, then back to the printer’s own CMYK. So the data the printer sees may not match the data Photoshop sees, since the printer driver’s CMYK->RGB conversion isn’t very good.

Third, consumer-grade inkjet printers don’t even use pure primary CMYK inks at all. In particular, the cyan ink that an inkjet printer uses isn’t really cyan; it’s too blue. This is done to get more vibrant, more saturated colors that consumer users like, at the expense of color accuracy. Professional inkjet printers use inks closer to CMYK primaries, and are easier to calibrate for press-accurate CMYK output.


Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
MR
Mike Russell
May 26, 2005
Tacit wrote:
… Photoshop’s out of gamut detection uses the current CMYK setup …

CMYK is indeed the default, but you may set the gamut warning to use any profile that may be used as a working space.

LabMeter, which is a free download from Curbemeister, uses this feature to plot the gamuts of any suitable profile.

Mike Russell
www.curvemeister.com
H
hearsay
May 26, 2005
Mike Russell wrote:
wrote:
[re conversion of RGB to CMYK]
By "Certain colors can not be reproduced in CMYK", I assume you meant out of gamut colors between color spaces. But some colors on a monitor that are not flagged as oog in PS still won’t show up in Epson inkjet prints, after all the fuzz of monitor calibration and custom printer profiles. Is the PS oog detection faulty? Aside from oog detection, are there other ways to find out what colors won’t print?

There are a host of technical issues with out of gamut colors. The ICC standard defines a "tag" that defines out of gamut colors.
But the gamut tag is not always included in a profile, and when it is, it is not used consistently by different manufacturers. So programs like Photoshop generally ignore the gamut tag, perferring instead to rely on color values calculated using the profile. One rather simple method of doing this is to see if converting the color back and forth gives the same result. For example, converting the out of gamut RGB (255,0,0) into CMYK and back again gives a different RGB value from the original (RGB(199,3,3), say). When this happens, that particular color is considered out of gamut.

When soft proofing with Epson inkjet profiles, I can see an obvious shift in some monitor colors that won’t be reproduced correctly in prints. Yet these colors are not detected as oog by PS. Does that mean the Epson profiles do not include the gamut tag? Is there a way to find out if a profile has a gamut tag?

There are other, better, ways to calculate out of gamut colors, and I suspect the Photoshop engine uses one of those. BTW, out of gamut colors are calculated by the engine, not by Photoshop itself. You can experiment by telling Photoshop to use the Microsoft (or Apple) ICM engine in your color prefs.

But this only says that the profile generates unique values for a particular color, and not whether the printer itself yields a different color when that color and colors close to it in value are printed. Given the limits of the current technology, particularly the poor support of the gamut tag, the only way to tell for sure is to print the colors, and scan them with a photometer or spectrophotometer. You can’t even look at the darn things to tell if they are different, because the differences are very subtle. No wonder there is so much confusion, so much being spent on calibration equipment, and relatively little result to show for it.

Confusing is an understatement. Take the above situation as an example. My working space is rgb, soft proofing is in rgb, the file is sent to the Epson as rgb, the Epson driver will print in six cmyk inks. Meanwhile when soft proofing in PS, there is an Info Palette option to show Proof Color (italic rgb). What is the meaning and use of Proof Color? IOW, what is the relationship between Actual Color and Proof Color? Adobe must have thought that Proof Color has some use.

But most of us realize that our inkjet printers do a pretty good job. If printers were watches, at this time in history they would accurate to a couple of minutes a day. As was the case with watches, there are those who require (or think that they require) greater accuracy, and are willing to pay for it. As has happened already with watches, at some point in the future printers will probably be extremely accurate and inexpensive. Until that happens, most of us can easily live comfortably with less than perfection.

Here are some more thoughts that I hope will give pause to some of you who have bought into the conventional wisdom that larger gamuts are always better than smaller ones.

1) What was the last out of gamut object you photographed? Blue sky, for example, is not really that saturated, particularly near the horizon where most of our cameras are pointed. Red objects – even bright bird plumage, is a far cry from RGB(255,0,0). For most of us, the answer to the question is "none".

2) RGB is not the last word in color spaces. Consider pure yellow objects, which are not all that uncommon, are not at all well represented in the RGB color space. For most monitors RGB(255,255,0) is brighter, but less saturated, than CMYK(0,0,100,0) will be in print. Magenta and cyan objects have similar problems.

Recent monitor developments have made an end run around this problem, resulting in the apparent miracle of a monitor capable of displaying the Adobe RGB color space directly. This is achieved by filtering the RGB phosphors to create purer colors, sharpening and stretching the three corners of the RGB gamut (to see these shapes, check out Curvemeister’s Labmeter, a free gamut plotter image). But even purity can have its limits, and the extermely sharp spectral characteristics of these monitors are bringing a new problem, viewer metamerism, to the forefront. With this latest advance, color consistency is literally in the eye of the beholder. The color on these monitors simply look funny to some people.
3) Consider that a larger gamut such as Adobe RGB sacrifices color gradation. An Adobe RGB image uses a smaller number of color values to represent the same range of colors than an sRGB image. This issue may be addressed by working in 16 bits, but there is a more serious problem to working in a large gamut space: the high probability that someone else may look at your image on an sRGB monitor and conclude that your work is too drab. Both of these issues – particularly the second one – are reasons for working in sRGB, particularly since real world objects such as pure blue sky do not come close to exceeding the gamut of even sRGB.

4) Print has a much smaller gamut than a CRT. The big money in photography is still in printed images, whether they be published images, or wall-sized art.

My suggestion, as always, is to trust what you can see and verify, and not spend too much time or money on getting your "watch" to run within one second of correct. Todays color and printer technology is excellent, and most of us – the vase majority – can live with its imperfections, provided we understand them, and base our understanding on common sense. —

Very well put. For hobbyists like myself, getting print colors "close" to monitor colors is all we need. But some colors I described above can be WAY off. That is like having a watch that is accurate to the minute most of the time, but can be off by hours some of the time. Very frustrating.

Will Crockett is another who choose sRGB over other wider gamut space as working space:

http://shootsmarter.com/infocenter.html
H
hearsay
May 26, 2005
Tacit wrote:
In article , wrote:

By "Certain colors can not be reproduced in CMYK", I assume you meant out of gamut colors between color spaces.

Yes, that’s correct. For example, pure RGB blue ain’t never going to be reproduced in CMYK.

But some colors on a monitor
that are not flagged as oog in PS still won’t show up in Epson inkjet prints, after all the fuzz of monitor calibration and custom printer profiles. Is the PS oog detection faulty? Aside from oog detection, are there other ways to find out what colors won’t print?

Photoshop’s out of gamut detection is remarkably good; however, there are many issues which may confound trying to identify out of gamut colors on an inkjet print.

For starters, Photoshop’s out of gamut detection uses the current CMYK setup; if this is incorrect (for example, if you’re using a SWOP profile, intended for printing presses, rather than a profile for your inkjet printer), Photoshop will show you the colors out of gamut for a printing press, not your printer.

Second, when you print CMYK to an inkjet printer, the printer’s drive software converts from CMYK to RGB, then back to the printer’s own CMYK. So the data the printer sees may not match the data Photoshop sees, since the printer driver’s CMYK->RGB conversion isn’t very good.
Third, consumer-grade inkjet printers don’t even use pure primary CMYK inks at all. In particular, the cyan ink that an inkjet printer uses isn’t really cyan; it’s too blue. This is done to get more vibrant, more saturated colors that consumer users like, at the expense of color accuracy. Professional inkjet printers use inks closer to CMYK primaries, and are easier to calibrate for press-accurate CMYK output.

Agreed with all your points. Please see my response to Mike’s post to see what’s been bugging me.
MR
Mike Russell
May 26, 2005
wrote:
[re working spaces, versus print spaces]

Confusing is an understatement. Take the above situation as an example.
My working space is rgb, soft proofing is in rgb, the file is sent to the Epson as rgb, the Epson driver will print in six cmyk inks. Meanwhile when soft proofing in PS, there is an Info Palette option to show Proof Color (italic rgb). What is the meaning and use of Proof Color? IOW, what is the relationship between Actual Color and Proof Color? Adobe must have thought that Proof Color has some use.

The meaning of actual and proof color, at least, is well defined. Actual color refers to the numeric pixel color values of your image. Proof color displays actual color values after converting from your working space to the last selected proof color space, as specified in View>Proof Setup. It’s like a one pixel "Convert to Profile", with the target color space set to your proof space.

The use and intent of Proof color is another issue. Photoshop is first and foremost a tool, and providing a motivation for each feature is in the documentation is difficult, and not necessarily Adobe’s responsibility.

One very powerful application for viewing proof color values is for verification of profile color operation. This is useful for people who produce color profiles, or who otherwise concern themselves with the input and output numeric values for conversions made by a particular profile. For example, set one info palette to actual", and another to "proof". Then move the cursor around your image to compare color values and look for trouble spots. Instead of saying "my colors look different", you could say that your epson color profile converts sRGB(255,0,0) to EpsonRGB(254,12,5).

Another use would be to preview what CMYK color values would be produced for various parts of your image, without having to first convert to the proof CMYK color space.

Very well put. For hobbyists like myself, getting print colors "close" to monitor colors is all we need. But some colors I described above can be WAY off. That is like having a watch that is accurate to the minute most of the time, but can be off by hours some of the time. Very frustrating.

Yes, or even a watch that simply stops some of the time. I’d be interested in exactly which colors look funny on your printer, how your printer is set up, etc. One quick think to try is to compare whatever profile setup you are using now with the Color Enhance setting for your printer. Terra cotta red, for example, happens to be a tricky color for some Epson papers. —
Mike Russell
www.curvemeister.com
H
hearsay
Jun 1, 2005
Mike Russell wrote:
wrote:
[re working spaces, versus print spaces]

Confusing is an understatement. Take the above situation as an example.
My working space is rgb, soft proofing is in rgb, the file is sent to the Epson as rgb, the Epson driver will print in six cmyk inks. Meanwhile when soft proofing in PS, there is an Info Palette option to show Proof Color (italic rgb). What is the meaning and use of Proof Color? IOW, what is the relationship between Actual Color and Proof Color? Adobe must have thought that Proof Color has some use.

The meaning of actual and proof color, at least, is well defined. Actual color refers to the numeric pixel color values of your image. Proof color displays actual color values after converting from your working space to the last selected proof color space, as specified in View>Proof Setup. It’s like a one pixel "Convert to Profile", with the target color space set to your proof space.

This part is easy to understand.

The use and intent of Proof color is another issue. Photoshop is first and foremost a tool, and providing a motivation for each feature is in the documentation is difficult, and not necessarily Adobe’s responsibility.
One very powerful application for viewing proof color values is for verification of profile color operation. This is useful for people who produce color profiles, or who otherwise concern themselves with the input and output numeric values for conversions made by a particular profile. For example, set one info palette to actual", and another to "proof". Then move the cursor around your image to compare color values and look for trouble spots. Instead of saying "my colors look different", you could say that your epson color profile converts sRGB(255,0,0) to EpsonRGB(254,12,5).

Here’s when things get complicated. How close should the Proof Color be relative to the Actual Color in a "good" profile (for a rgb printer like Epson)? If there is a big mismatch, what can you do about it?

For the Epson printer that uses six/eight inks, I think the problem just gets more complicated. Since the Proof Color rgb values will eventually be used to "drive" the inks by the Epson driver, the numbers may be very different from the Actual Color values.

Another use would be to preview what CMYK color values would be produced for various parts of your image, without having to first convert to the proof CMYK color space.

If the working space is cmyk and the output is cmyk press printing, comparing Actual and Proof colors may make more sense. I’m unfamiliar with press printing, so some guess here.

Very well put. For hobbyists like myself, getting print colors "close" to monitor colors is all we need. But some colors I described above can be WAY off. That is like having a watch that is accurate to the minute most of the time, but can be off by hours some of the time. Very frustrating.

Yes, or even a watch that simply stops some of the time. I’d be interested in exactly which colors look funny on your printer, how your printer is set up, etc. One quick think to try is to compare whatever profile setup you are using now with the Color Enhance setting for your printer. Terra cotta red, for example, happens to be a tricky color for some Epson papers.

It took me a while to come up with a reasonable example. Here’s a small crop from an unedited scan file to illustrate a typical monitor/print mismatch problem. The crt monitor has been calibrated with a Spyder.

http://pg.photos.yahoo.com/ph/roger8231/detail?.dir=/3b76&am p;.dnm=7ac1.jpg&.src=ph

In proofs and prints, A and B are the problem areas, while C and D are acceptable for my purpose. Using A as an example, here are its rgb values before and after Soft Proofing with the Epson 2200 hwm profile (first with perceptual intent, and then with relative colorimetric intent.)

Actual Color = 57_30_24
Proof Color (perceptual intent) = 86_19_6
Proof Color (relative colorimetric intent) = 64_7_12

While the perceptual intent proof is more pleasing, A and B lose their shadow impact. The relative colorimetric intent proof is just dull, but the B area retains some shadow. Test prints (convert to profiles and no color management at Epson) match pretty closely to the proofs.

If you have the 2200 (or 1280) Epson profiles, do you consider the proofs and prints of this image "closely matching" the monitor image? (i.e. This is as good as it gets with these printers and profiles.) What, if anything, do the Proof Colors tell you? Is the problem because A and B are out of gamut (no oog is detected)? Can a custom profile fix this kind of problem? For those who don’t use profiles, can their prints of this image match what they see on their monitors? If yes, how?
MR
Mike Russell
Jun 2, 2005
wrote:
[re relation of original RGB image color to a particular printer’s proof color]

Here’s when things get complicated. How close should the Proof Color be relative to the Actual Color in a "good" profile (for a rgb printer like Epson)? If there is a big mismatch, what can you do about it?

The actual color values are less important than the answers to these questions:

1) Is the profile of excellent quality?

2) How much are adjacent color values changing in the proof when you modify your original color values slightly. I think of this as the amount of "elbow" room a particular color has in the proof, and it amounts to how close to the edge of the printer’s gamut your desired color is?

3) Is the printer color space unduly distorted in the particular area where your color falls, or are there other topological problems with the lightest or darkest areas of the gamut?

Using Photoshop’s info palette’s proof color feature only gives you an ant’s eye view of what is occuring with your color. Curvemeister’s free download, LabMeter, addresses this issue more globally, since you can locate the Lab coordinates of your color on the image, and see if you are located in a "fat" part of the gamut, or off in "blue Florida" (my name for the dark peninsula of blue that most RGB and CMYK profiles have in the darker range of the profile, known as the threequartertone), or the yellow Aleutians. Some bits of gamut are even located on little "islands", or bits of ragged coastline, and although these tend to be areas of very low luminance, it strikes me that these areas would not be very useful in actual printing.

For the Epson printer that uses six/eight inks, I think the problem just gets more complicated. Since the Proof Color rgb values will eventually be used to "drive" the inks by the Epson driver, the numbers
may be
very different from the Actual Color values.

If you are interested in this sort of thing, Epson has described how this is done, at least in part, in their patent documents. You’re correct that it is complex, but the nice thing is there is no need to worry about it.

Another use would be to preview what CMYK color values would be produced for various parts of your image, without having to first convert to the proof CMYK color space.

If the working space is cmyk and the output is cmyk press printing, comparing Actual and Proof colors may make more sense. I’m unfamiliar with press printing, so some guess here.

The numeric comparison is of more interest to folks who work more directly with the numbers, though the numbers can be of interest to anyone who is curious about the inner workings of profiles. They are also helpful for discussing printing problems, as in this case.

[re actual colors that don’t print well]

It took me a while to come up with a reasonable example. Here’s a small
crop from an unedited scan file to illustrate a typical monitor/print mismatch problem. The crt monitor has been calibrated with a Spyder.
http://pg.photos.yahoo.com/ph/roger8231/detail?.dir=/3b76&am p;.dnm=7ac1.jpg&.src=ph
In proofs and prints, A and B are the problem areas, while C and D are acceptable for my purpose.

I’m getting the following values from your scan for these locations. BTW There is no embedded profile in your image, so I’m assuming you are using Adobe RGB because the image looks dull as dishwater in sRGB. The color numbers were copy/pasted using software, I did not type them in manually :-):

A RGB(54,29,25)
B RGB(59,31,19)
C RGB(25,20,16)
D RGB(88,56,36)

and for use with LabMeter, which is a free curvemeister download, here are the same colors in Lab:

A Lab(13,18,12)
B Lab(15,19,16)
C Lab(5,1,2)
D Lab(27,19,24)

C is relatively dark, and requires less color accuracy because the eye is more forgiving of very dark colors. D is the brightest of the four colors, so it occupies a wider part of the gamut, giving it a better shot at retaining its hue for a good match. This turns out to be important for this particular profile.

Using A as an example, here are its rgb
values before and after Soft Proofing with the Epson 2200 hwm profile (first with perceptual intent, and then with relative colorimetric
intent.)
Actual Color = 57_30_24
Proof Color (perceptual intent) = 86_19_6
Proof Color (relative colorimetric intent) = 64_7_12

These are very interesting numbers, for a couple of reasons. First, they are "fatter" (brighter and more saturated) than the corresponding original numbers. I was very puzzled by this, and downloaded some of the Epson 2200 profiles from www.epson.com. The profiles that I downloaded are horrible. If the yours are similar, this explains the problem.

The quick check is to look at the individual channels – red is not bad, but green and especially blue show very prominent banding and light spots in just the areas you are mentioning. In particular, the shadow as you approach the chin rest gets lighter, instead of darker, for these channels!

You may verify this for yourself more systematically as follows. Lay down a gradient – I recommend setting dither off and smoothness to zero in the profile editor to get a clean gradient. Then convert it using one of the Epson profiles. Look at the green and blue channels, and you will see substantial banding near the threequartertone, right in the area of concern for the colors you mentioned.

The free Profile Plotter action at Curvemeister.com will do this more systematically, producing a graph of all three channels. If your profile is like mine, you will see some rather nasty bends in the red and green curves, right where the trouble is.

While the perceptual intent proof is more pleasing, A and B lose their shadow impact. The relative colorimetric intent proof is just dull, but the B area retains some shadow. Test prints (convert to profiles and no color management at Epson) match pretty closely to the proofs.

Yes, the banding is worse in the RelCol profile.

If you have the 2200 (or 1280) Epson profiles, do you consider the proofs and prints of this image "closely matching" the monitor image? (i.e. This is as good as it gets with these printers and profiles.) What, if anything, do the Proof Colors tell you? Is the problem because A and B are out of gamut (no oog is detected)?

The proof colors tell me that the profile is making the shadows substantially lighter, even adding an apparent glow to the darkest areas of the image that simply does not belong there.

Can a custom profile fix this kind of problem?

Yes, it can, however there are substantial hazards to using a scanner, as I suspect happened for these particular profiles, rather than a spectrophotometer or good quality colorimeter to generate a printer profile. Shadows are easy to print accurately, but difficult to scan accurately, so scanner based profile packages are fighting an uphill battle when it comes to generating accurate profiles for the darkest 25% of the image.

For those who don’t use profiles, can their prints
of this image match what they see on their monitors? If yes, how?

Use of a good profile is great – and you may use the profile plotter action to judge this for yourself and ensure that there are no sharp bends or other irregularities in the shadows. Otherwise, try using the PhotoEnhance mode of the Epson driver and see if you like the results. Although not profile based, it is capable of good results provided you stick to the Epson inks and the paper types that are mentioned in the driver.

If your profiles do not show this problem, it is still possible that something else is wrong – if you believe this is the case, perhaps you could make the icm files available somewhere and I could look at them more closely. Otherwise, all you need to do is get hold of some better profiles (or use PhotoEnhance) and you’ll be on the air with better looking shadows.

Thanks for an interesting problem.

Labmeter is located here:
http://www.curvemeister.com/tutorials/LabMeter/index.htm

and the Profile Plotter is here:
http://www.curvemeister.com/downloads/profileplotter/index.h tm

The RGB and Lab values were converted to text using the Curvemeister plugin. This functionality, and many more color related features, is supported in the demo version:
http://www.curvemeister.com/downloads/cmdemo/index.html


Mike Russell
www.curvemeister.com
H
hearsay
Jun 3, 2005
Mike Russell wrote:

Thanks for an interesting problem.

I should thank you for taking your time to look at the image and follow up in detail. If this "interesting" problem is caused by these popular Epson printer profiles, I should not be the only one troubled by it. Since no one else is participating in this thread, can we continue off line? That way, I can send you images and profiles, etc. I do have many comments and questions.
H
Hecate
Jun 3, 2005
On Wed, 01 Jun 2005 13:36:40 GMT, wrote:

Here’s when things get complicated. How close should the Proof Color be relative to the Actual Color in a "good" profile (for a rgb printer like Epson)? If there is a big mismatch, what can you do about it?
Here’s where you go wrong and why you’re having trouble fully understanding it. The Epson printer isn’t an RGB printer. No printers are RGB printers. Printers are CMYK devices. The fact that you need to send the Epson an RGB files doesn’t change the fact that it prints CMYK.

Hope that helps,



Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…
MR
Mike Russell
Jun 4, 2005
wrote:
Mike Russell wrote:

Thanks for an interesting problem.

I should thank you for taking your time to look at the image and follow up in detail.

If this "interesting" problem is caused by these popular Epson printer profiles, I should not be the only one troubled by it.

There are hundreds of people scratching their heads over poor profiles.

Since no one else is participating in this thread, can we continue off line? That way, I can send you images and profiles, etc. I do have many comments and questions.

I’d like to continue this discussion in some sort of public forum. I think the problem is of wide interest, in spite of the lack of other people participating, I think there are some lurkers who are benefitting. The curvemeister yahoo group is another possibility. The group has an upload area for files and images, and there are other experienced people who will chime in.

Mike Russell
www.curvemeister.com
..
H
hearsay
Jun 9, 2005
Been awhile and let me catch up.

Really appreciate your comments on Proof Colors, and the utilities at your site. However, the bottom line remains how to get a good print from the image sample I posted. I would much prefer to work on my prints than on profiles. So I’ll skip to the meaty part.

Mike Russell wrote:
wrote:

Can a custom profile fix this kind of problem?

Yes, it can, however there are substantial hazards to using a scanner, as I suspect happened for these particular profiles, rather than a spectrophotometer or good quality colorimeter to generate a printer profile. Shadows are easy to print accurately, but difficult to scan accurately, so scanner based profile packages are fighting an uphill battle when it comes to generating accurate profiles for the darkest 25% of the image.

Since I only use Epson media and a few paper, I’m interested in getting the custom profiles built rather than rolling my own. Drycreek and Cathy’s seem to get mentioned a lot. Do you happen to know how they build their profiles and how good their profiles are?

For those who don’t use profiles, can their prints
of this image match what they see on their monitors? If yes, how?

Use of a good profile is great – and you may use the profile plotter action to judge this for yourself and ensure that there are no sharp bends or other irregularities in the shadows. Otherwise, try using the PhotoEnhance mode of the Epson driver and see if you like the results. Although not profile based, it is capable of good results provided you stick to the Epson inks and the paper types that are mentioned in the driver.

Should my working space be Adobe rgb or srgb if I want to print from the PhotoEnhance mode? My guess is that it matters not. Using this method, does it make sense to Soft Proof? Is there a way to see (or find out) what colors on the monitor image that won’t print with this method? OK, the real question is how closely will the prints from using the PhotoEnhance mode match what is on the monitor?

If your profiles do not show this problem, it is still possible that something else is wrong – if you believe this is the case, perhaps you could make the icm files available somewhere and I could look at them more closely. Otherwise, all you need to do is get hold of some better profiles (or use PhotoEnhance) and you’ll be on the air with better looking shadows.

By icm files, I assume you meant profile files? Epson provides different sets of profiles for the 2200. Those found in the following link are supposed to be the best, they are 10x bigger than those on the CD. The one I used in this discussion is from the download: EnhancedMatte2880MB.

http://www.epson.com/cgi-bin/Store/EditorialAnnouncement.jsp ?BV_UseBVCookie=yes&oid=42114986

BTW, I have added the same test image with srgb profile. It looks better but the numbers are the same, as expected.

http://pg.photos.yahoo.com/ph/roger8231/detail?.dir=/3b76&am p;.dnm=3450.jpg&.src=ph
H
hearsay
Jun 9, 2005
Not quite. I do understand the Epson prints in cmyk, but its driver expects a rgb file. I stand corrected in calling it a rgb printer. With that settled, do you have anything to add to Mike’s response to my answer "How close should the Proof Color be relative to the Actual Color in a "good" profile…?"

Hecate wrote:
On Wed, 01 Jun 2005 13:36:40 GMT, wrote:

Here’s when things get complicated. How close should the Proof Color be relative to the Actual Color in a "good" profile (for a rgb printer like Epson)? If there is a big mismatch, what can you do about it?
Here’s where you go wrong and why you’re having trouble fully understanding it. The Epson printer isn’t an RGB printer. No printers are RGB printers. Printers are CMYK devices. The fact that you need to send the Epson an RGB files doesn’t change the fact that it prints CMYK.

Hope that helps,



Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…
H
hearsay
Jun 9, 2005
Mike Russell wrote:
There are hundreds of people scratching their heads over poor profiles.

Why don’t they jump in this thread?
H
Hecate
Jun 9, 2005
On Thu, 09 Jun 2005 14:43:31 GMT, wrote:

Not quite. I do understand the Epson prints in cmyk, but its driver expects a rgb file. I stand corrected in calling it a rgb printer. With that settled, do you have anything to add to Mike’s response to my answer "How close should the Proof Color be relative to the Actual Color in a "good" profile…?"
Pretty close given you are looking at an RGB device (monitor) and will get a print (CMYK). I use soft proofing all the time, and make sure I deal with any out of gamut colours before printing.



Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…
H
Hecate
Jun 9, 2005
On Thu, 09 Jun 2005 14:37:51 GMT, wrote:

Should my working space be Adobe rgb or srgb if I want to print from the PhotoEnhance mode? My guess is that it matters not.

It does. sRGB has a much narrower colour space. AdobeRGB has a wider colour space *and* the colour space maps more closely to CMYK than sRGB.

Using this method,
does it make sense to Soft Proof? Is there a way to see (or find out) what colors on the monitor image that won’t print with this method? OK, the real question is how closely will the prints from using the PhotoEnhance mode match what is on the monitor?

Yes. And yes. Use softproofing and have PS show Out Of Gamut colours.



Hecate – The Real One

Fashion: Buying things you don’t need, with money
you don’t have, to impress people you don’t like…
MR
Mike Russell
Jun 9, 2005
wrote:
Mike Russell wrote:
There are hundreds of people scratching their heads over poor profiles.

Why don’t they jump in this thread?

It’s a fair question, and there have been threads by other people on this subject before, here and on other forums.

But the bigger reason is that most of those hundreds of people do not use Usenet at all. In part because they are too busy, and also because the atmosphere here tends to be combative, to say the least 🙂 —
Mike Russell
www.curvemeister.com
MR
Mike Russell
Jun 9, 2005
wrote:
Been awhile and let me catch up.

Really appreciate your comments on Proof Colors, and the utilities at your site. However, the bottom line remains how to get a good print from the image sample I posted. I would much prefer to work on my prints than on profiles. So I’ll skip to the meaty part.

Careful – you might actually get somewhere if you concentrate on the actual image. 🙂
….
Since I only use Epson media and a few paper, I’m interested in getting the custom profiles built rather than rolling my own. Drycreek and Cathy’s seem to get mentioned a lot. Do you happen to know how they build their profiles and how good their profiles are?

The Digital Printer profiles at DryCreek, do appear to be of good quality. Their articles are accurate and well-written. This may mean their custom printer profiles are good. I know nothing about Cathy’s. Having said all that, keep in mind that you don’t buy a profile, you subscribe to it, and you’ll need to recalibrate every once in a while, as often as once a month if you want real accuracy.

Another alternative is to set your printer to PhotoEnhance4 and print a gray ramp. If black white, and all the intervening grays are accurate, how far off can the rest of your colors be? Answer: not very.

Should my working space be Adobe rgb or srgb if I want to print from the PhotoEnhance mode? My guess is that it matters not.

You got it. The bigger answer is to take one of your problem images and print it. Opinions vary among reasonable people on this, and consensus is rare, but your conclusion after looking at your own print should hold a lot of weight, for yourself at least.

Using this method,
does it make sense to Soft Proof? Is there a way to see (or find out) what colors on the monitor image that won’t print with this method?

Pick a similar Epson profile to look for out of gamut colors, but print with PhotoEnhance4. All of the colors will print, of course. People are much more sensitive to gradations in brightness than hue, and for this reason gamut size is of much less importantance than some believe.

OK, the real question is how closely will the prints from using the PhotoEnhance mode match what is on the monitor?

Black and white should match. You should be able to spot any overall color cast, and make judgements about shadow detail, and the overall brightness of the image. The printer and screen, however, will not look identical.

You can get closer with additional technology in the form of calibration and a standardized viewing booth for your prints. IMHO this is chasing an expensive wil o the wisp, unless you are a professional prepress house with multiple empoloyees.

By icm files, I assume you meant profile files? Epson provides different sets of profiles for the 2200. Those found in the following
link are
supposed to be the best, they are 10x bigger than those on the CD. The one I used in this discussion is from the download:
EnhancedMatte2880MB.
http://www.epson.com/cgi-bin/Store/EditorialAnnouncement.jsp ?BV_UseBVCookie=yes&oid=42114986

This package contains four profiles. The two 2880 ones have a band in the green shadow where it could be causing problems for your image. Which one do you use, and do you use Perceptual or Relative Colorimetric?

BTW – you can test for banding yourself by laying down a gradient, converting to the profile, and then looking at each channel. Photoshop makes it challenging to create a "clean" gradient from 0 to 255, so I have provided a png file:

BTW, I have added the same test image with srgb profile. It looks better but the numbers are the same, as expected.
http://pg.photos.yahoo.com/ph/roger8231/detail?.dir=/3b76&am p;.dnm=3450.jpg&.src=ph

Yes, this is much more saturated. I’m not sure what you mean about the numbers being the same, though. The sRGB values are considerably more saturated.

Mike Russell
www.curvemeister.com
C
Clifford
Jun 11, 2005
Hi

It is sometimes better, and less stressful, to accept the image from the printer having ‘considered’ the image on the screen.

Cheers

On 10/6/05 12:21 am, in article
ia4qe.26520$, "Mike Russell"
wrote:

wrote:
Been awhile and let me catch up.

Really appreciate your comments on Proof Colors, and the utilities at your site. However, the bottom line remains how to get a good print from the image sample I posted. I would much prefer to work on my prints than on profiles. So I’ll skip to the meaty part.

Careful – you might actually get somewhere if you concentrate on the actual image. 🙂


Since I only use Epson media and a few paper, I’m interested in getting the custom profiles built rather than rolling my own. Drycreek and Cathy’s seem to get mentioned a lot. Do you happen to know how they build their profiles and how good their profiles are?

The Digital Printer profiles at DryCreek, do appear to be of good quality. Their articles are accurate and well-written. This may mean their custom printer profiles are good. I know nothing about Cathy’s. Having said all that, keep in mind that you don’t buy a profile, you subscribe to it, and you’ll need to recalibrate every once in a while, as often as once a month if you want real accuracy.

Another alternative is to set your printer to PhotoEnhance4 and print a gray ramp. If black white, and all the intervening grays are accurate, how far off can the rest of your colors be? Answer: not very.

Should my working space be Adobe rgb or srgb if I want to print from the PhotoEnhance mode? My guess is that it matters not.

You got it. The bigger answer is to take one of your problem images and print it. Opinions vary among reasonable people on this, and consensus is rare, but your conclusion after looking at your own print should hold a lot of weight, for yourself at least.

Using this method,
does it make sense to Soft Proof? Is there a way to see (or find out) what colors on the monitor image that won’t print with this method?

Pick a similar Epson profile to look for out of gamut colors, but print with PhotoEnhance4. All of the colors will print, of course. People are much more sensitive to gradations in brightness than hue, and for this reason gamut size is of much less importantance than some believe.
OK, the real question is how closely will the prints from using the PhotoEnhance mode match what is on the monitor?

Black and white should match. You should be able to spot any overall color cast, and make judgements about shadow detail, and the overall brightness of the image. The printer and screen, however, will not look identical.
You can get closer with additional technology in the form of calibration and a standardized viewing booth for your prints. IMHO this is chasing an expensive wil o the wisp, unless you are a professional prepress house with multiple empoloyees.

By icm files, I assume you meant profile files? Epson provides different sets of profiles for the 2200. Those found in the following
link are
supposed to be the best, they are 10x bigger than those on the CD. The one I used in this discussion is from the download:
EnhancedMatte2880MB.
http://www.epson.com/cgi-bin/Store/EditorialAnnouncement.jsp ?BV_UseBVCookie=ye s&oid=42114986

This package contains four profiles. The two 2880 ones have a band in the green shadow where it could be causing problems for your image. Which one do you use, and do you use Perceptual or Relative Colorimetric?
BTW – you can test for banding yourself by laying down a gradient, converting to the profile, and then looking at each channel. Photoshop makes it challenging to create a "clean" gradient from 0 to 255, so I have provided a png file:

BTW, I have added the same test image with srgb profile. It looks better but the numbers are the same, as expected.
http://pg.photos.yahoo.com/ph/roger8231/detail?.dir=/3b76&am p;.dnm=3450.jpg&.src=p> h
Yes, this is much more saturated. I’m not sure what you mean about the numbers being the same, though. The sRGB values are considerably more saturated.

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