Why do CMYK process builds get changed?

[gordo]

I have two questions for you. The image that's causing the questions is attached.

1. I have a CMYK image that has an embedded profile: U.S. Web Coated (SWOP) v2
If I open it in PShop (CS3) with "Use the embedded profile (instead of the working space)" the image opens up and every thing is correct.
But, ff I open it with "Convert document's colors the working space" the image opens up and C, M, Y are the same - but the K channel appears to have been reseparated since it now has C, M, Y tones and the K has changed.

I thought that CMYK values weren't supposed to change (and they didn't for CMY) so, what's going on?

2. What would cause only the 100% K patch in this graphic to change to 4/C in a Rampage workflow?

thx, gordo

PS This question is also posted in the Rampage area.

 

[Correct Color]

That's the way it's supposed to work.

If you got the different-CMYK-space dialogue, then obviously you've got your CMYK working space set to something other than SWOP. So, what happens is the color engine looks at the L*a*b* value of each pixel in your image and assigns it the closest CMYK match available in your working space.

But all it knows is L*a*b*. It doesn't know your black only patches are black only. So it re-renders them in all four colors. (That's the main reason so many people love device links. They skip the trip through L*a*b*). However, the CMY patches are still CM&Y, so unless you're moving to a dramatically different space with substantially different primaries, it's likely they will stay pretty much the same.

As to Rampage, there's probably a setting in it somewhere telling it to leave black only grays as black only.

Mike Adams
Correct Color

 

[mattbeals]

would it not be acceptable to preserve the embedded profile and then simply apply the working cmyk profile?

 

[Correct Color]

Yup. Actually Adobe calls it "assign." But that's what you'd want to do to preserve the color numbers and move to a different profile. Good in a case like this. Generally very, very, bad in a workflow.

(Edited to add: Actually, all "Discard the embedded profile (don't color manage)"--the other option in the embedded-profile-mismatch dialogue--does is assign the working space profile, so in this case you could just click that. But I'm so philosophically opposed to the wording of that that I can't quite bring myself to ever recommend selecting it.)

 

[Stephen Marsh]

(Edited to add: Actually, all "Discard the embedded profile (don't color manage)"--the other option in the embedded-profile-mismatch dialogue--does is assign the working space profile, so in this case you could just click that. But I'm so philosophically opposed to the wording of that that I can't quite bring myself to ever recommend selecting it.)

Sorry to nit-pick...however assign has a specific meaning when it comes to Adobe software:

Just to clarify the bolded red point in the above quote, the profile is not "assigned" - it is "assumed" to be the working CMYK profile. This is a big difference in policy, not just semantics.

When the image is saved as, the profile inclusion option is unchecked/disabled to retain the "non-colour managed" status of the file. If the profile was assigned, then this would be a firm decision to include the profile and the profile inclusion option would then be checked/enabled in the save as dialog box.

The "don't colour manage" step does not "assign" a profile, it strips out the profile (even though the option lives under the "assign profile" command).


Sincerely,

Stephen Marsh

 

[Lukas Engqvist]

In Illustrator or InDesign there is the option to preserve numbers. Personally I prefer to treat all CMYK as preserve numbers and if I want to colour manage to use RGB (or LAB). In Acrobat, and some APOGEE there is the options to colour manage but preserve blacks (greys)

 

[tmiller_iluvprinting]

It is risky setting Photoshop's policies to convert to the working spaces on the fly. There may be certain circumstances where this would be an advantage, but I would never recommend it. As far as RAMPage is concerned, we have never had an issue with K only being converted to 4/color in RAMPage. We have, however had issues when exporting pdf's out of Quark with color management settings enabled. Turn off all CM settings in Quark. We have also had issues with .eps files saved out of Photoshop with Transfer functions and PostScript Color Management enabled, again, disable these before saving.
Regards,
Todd

 

[Correct Color]

Stephen,

We'll probably have to agree to disagree--at least on how to define what happens. And while you do have a point, I'll tell you why I disagree:

I actually started--when I wrote what you highlighted--to include some qualifier like "for all intents and purposes" or "in essence" before 'assigns.'

But I decided not to just for clarity's sake. Because the fact is, by accepted color management terminology, assigning the working space profile is exactly what clicking on that option does.

And as far as I'm concerned, one of the keys to making color management work is making it absolutely application independent, and so for that reason, no one, not Adobe or anyone else, gets to invent their own terms for color management processes, or use color management terms in their own unique way.

When you open a file using that option, Photoshop does assign the working color space values to every pixel in the file, and since Photoshop is by its very nature always never the final destination of any file, more importantly when the file is saved--file embedded or not--its pixels relate as worked in Photoshop in that session only to that color space.

Which makes it the functional equivalent of 'assign' to me, so rather than muddy the waters by saying "the functional equivalent of assign" I'm going to just go with "assign."


Mike

 

[gordo]

This is what the document creator said they did:

"In my Illustrator Preferences, all blacks are to display and output as rich blacks. It didn't occur to me to change that setting. And the printer's prepress didn't override the spec.

I didn't place the chart into any Quark or InDesign document; I sent the original .ai file."

Does that explain it?

best, gordo

 

[Correct Color]

Does that explain it?

I doubt it. The Illustrator black preferences only pertain to vector elements created in the Illustrator document. Depending on whether you import or link to files you incorporate into an Illustrator document you'll either keep the original profile in an image or replace it with the document profile, but in this case, if I'm understanding what you're asking, you've got a CMYK .jpg--the one you linked to--that you opened in Photoshop, and got the results you got depending on how you opened it.

Which, again, are exactly the results you should expect. When you ask PS to change from one CMYK space to another it's going to render the black as 4cp. Lots of people don't like that but it is the way it works.

It renders the CMY as 4cp as well, it's just that while there's a L*a*b* equivalent for every neutral patch (black only) that includes all four colors, if your primaries are ISO standard colors and densities from one space to the next, then the closest CMYK equivalent is not likely to have any of the other colors in it.

 

[gordo]

I doubt it. The Illustrator black preferences only pertain to vector elements created in the Illustrator document. Depending on whether you import or link to files you incorporate into an Illustrator document you'll either keep the original profile in an image or replace it with the document profile, but in this case, if I'm understanding what you're asking, you've got a CMYK .jpg--the one you linked to--that you opened in Photoshop, and got the results you got depending on how you opened it.

I might not have been clear. The printer was supplied a CMYK illustrator file. There's no jpeg or PShop involved. The PShop question was a separate issue.

thx, gordon

 

[Correct Color]

Oh.

Well, that--his Illustrator black preference--would likely explain the black patch only converting to CMYK in Rampage.

 

[Stephen Marsh]

Stephen,

We'll probably have to agree to disagree--at least on how to define what happens. And while you do have a point, I'll tell you why I disagree:

I agree that we will have to agree to disagree Mike.

I actually started--when I wrote what you highlighted--to include some qualifier like "for all intents and purposes" or "in essence" before 'assigns.'
But I decided not to just for clarity's sake. Because the fact is, by accepted color management terminology, assigning the working space profile is exactly what clicking on that option does.

This is the sticking point for me, clicking that option (don't colour managea) does not assign, as no profile is assigned to the file. The working space for that colour mode is simply assumed. So in my opinion, there is a big difference between assigning and assuming, which is why I can't simply agree with this statement.

A file that has a profile assigned to it will have that profile tagged to the file. A file that is "non colour managed" will not have any profile tagged to the file. The working space is assumed and will be assumed to be different depending on the colour settings of the installation opening the file.


Sincerely,

Stephen Marsh