Working with CMYK images made with the wrong colour profile

[ukzembla]

Hi, 

I'm working on an illustrated colour book, which should be exported with the FOGRA52 profile. The client has said that TAC should be 260% max, though I believe FOGRA52 enforces a max of 300. The client has provided me with CMYK PSDs just using the default CMYK profile (U.S. Web Coated (SWOP) v2). I suspect the illustrator may just not know much about colour profiles, and I won't be able to get new files from them. I usually get images as RGB, which InDesign then converts upon export to the output profile, but I believe if I import CMYK images into InDesign, then when I have "preserve numbers" set on export (which I am still too scared to change), InDesign will preserve the SWOP profile from the Photoshop files, rather than convert to FOGRA52. So... should I be going into each PSD file, going to convert to profile, then converting to FOGRA52, or is that fraught? And for the TAC, if it's actually 260 max, what's the best (easyish) way to achieve this without spending hours recolouring images? My Photoshop skills are OK, but I'm certainly not an illustrator. I'm not sure if this is something printers can often do in house or not.

Thanks for your help in the dark arts of colour reproduction and profiles…

[Frans v.d. Geest]

Yes, only RGB images are converted when outputting from InDesign. But indeed, use Photoshop and then Convert to Profile and use the 260% TAC profile. Then place those images in InDesign.

[ukzembla]

Thanks for the help. The only thing is that the printers asked both for FOGRA52 and a max TAC of 260%, but I'm pretty sure FOGRA52 has a max TAC of 300%. Is there a reasonably straightforward way around this?

[Frans v.d. Geest]

Yes, Fogra 52 (PSOuncoated_v3) has indeed a TAC of 300%, Fogra 39 and Fogra 47 have 260% TAC

[ukzembla]

Hm, so when the printer asks for FOGRA52 with a TAC of 260%, what should a sensible person do? I'm guessing the two you mention have other characteristics aside from the TAC, so how to restrict TAC without messing up colours? Thanks again for all your input.

[Test Screen Name]

"I believe if I import CMYK images into InDesign, then when I have "preserve numbers" set on export (which I am still too scared to change), InDesign will preserve the SWOP profile from the Photoshop files, rather than convert to FOGRA52."

Quite the opposite. If you say "preserve numbers" it keeps the numbers (ink values) that are right for SWOP, but changes the label to FOGRA52, so the RIP won't know to convert anything. It is used as a desperate last resort only, when you know the CMYK values were correct. (I'm curious Frans - you say that CMYK is not converted, then what does this option apply to?)

[Frans v.d. Geest]

"Preserve numbers" says it all: it preserves the CMYK values. Otherwise, Black K text would be converted to another profile and would become a CYMK black instead of K for instance or a 20% Cyan only would become a CMYK build.

Colour management is designed for RGB to CMYK managment. So if you keep your images in RGB they will be converted to the right profile on output from InDesign; but CMYK values (so images in CMYK mode as well) will be 'preserved'!

But when you have CMYK images you want to convert? Use Photoshop to Convert to profile. Then when you place those in InDesign they are already in the 'right' values and will pe passed as such with  outp from InDesign.

[rob day · Accepted solution]

when I have "preserve numbers" set on export (which I am still too scared to change), InDesign will preserve the SWOP profile from the Photoshop files, rather than convert to FOGRA52.

Preserve Numbers is a bit misleading, it only preserves the numbers of document CMYK colors—native InDesign swatches and colors, and placed CMYK images with no embedded profile (or a profile that matches your ID document’s assigned profile). All other color—CMYK with a conflicting profile, or any RGB color—would be converted to new numbers.

So the expected export behavior would depend on the Color Settings’ CMYK policy you used when creating the document. If the document was set up with the CMYK Policy set to Preserve Embedded Profiles, the placed SWOP CMYK images would get converted to FOGRA 52 on an export set to Convert to Destination (Preserve Numbers), and the native CMYK swatch numbers would be preserved no matter what the document’s assigned profile. If your Policy was set to Preserve Profiles (Ignore Linked Profiles), the placed SWOP CMYK images would have their CMYK profile ignored and there would be no conversion on the export.

You are right FOGRA 52 is an uncoated profile and allows up to 300% on a conversion, so a conversion from SWOP (or RGB) to FOGRA 52 would not limit the ink to 260%. Are you in direct communication with the printer? If they are asking for a 260% limit, but are expecting FOGRA 52, they don’t understand how conversions work.

[ukzembla]

Well, it seems requests like this keep coming up with different commercial printers in Europe, so it definitely wasn't a one-off… So my choices are for situations like this: 1) use a different printer (not my prerogative as I'm supplying print-ready PDFs, not in charge of printing or paying for it); 2) try to get more info out of the printers (can be frustrating as I usually get one-line answers without too much help, and often English isn't a first language); 3) try to fix the TAC myself somehow (I've been told that certain types of paper need different TACs, so perhaps that's the issue). I'm mainly concerned that the colours come out as intended (so I don't want to use a totally different profile for the wrong printer but with the right TAC). In that situation where you don't have that much choice, what would people here do? Is there such a thing as the standard FOGRA52 profile but with a modified TAC? The alternatives I can think of are: convert images to CMYK using another profile (e.g. GRACOL, which is 280 TAC) in Photoshop, then converting that to FOGRA52. Which is a bit of a hassle and I'm unclear how well it would come out – or altering the colours levels myself, which I'm not keen to do.

From looking around, it seems that VIGC created some lower TAC versions of standard profiles at the time for this very purpose (there's still one knocking around for FOGRA47 with a TAC of 260), but it doesn't look like it's been updated, and various links I've found online are now dead. Is FOGRA47 with that TAC a reasonable substitute, if the printer is unable to provide their own ICC profile? 

[rob day]

The alternatives I can think of are: convert images to CMYK using another profile (e.g. GRACOL, which is 280 TAC) in Photoshop, then converting that to FOGRA52. Which is a bit of a hassle and I'm unclear how well it would come out – or altering the colours levels myself, which I'm not keen to do.

I would never make CMYK-to-CMYK conversions.

The color appearance of Uncoated GRACol and PSO Uncoated FOGRA52 is quite similar, so why not use GRACol? Or leave the images as profiled RGB and let the printer handle the conversion in the RIP, in that case the press color profile and TAC will be their responsibility.

Here is the same CMYK image with the two different profiles assigned:

[ukzembla]

Thanks. GRACOL is still 280, but I'm guessing would work OK for the most part (i.e. there may be some bits between 260-280, but as long as it's not massive areas I'm guessing I'd be OK). But I'm also provided with images in CMYK from time to time (sometimes with a sensible profile, sometimes just the generic default…), so may need to convert profile? I've read conflicting things on whether CMYK -> CMYK is a bad idea. Or are you suggesting converting to Adobe RGB in Photoshop, using that and then exporting from InDesign to (e.g.) GRACOL?

I've been typesetting books for years, but am still getting my head around printing and colour management; it doesn't help that printers give sparse, unhelpful or totally outdated advice! I think most printers aren't too familiar with standard design / colour management workflows in Photoshop / InDesign. 

[rob day]

Color managed conversions can happen at 3 different points in the workflow—inside of Photoshop, on export to PDF, or in the print RIP. If the destination profile and rendering intents are the same for all, there would be no difference in color outputs.

If the printer expects you to control the TAC, but won’t or can’t give you a press profile, I would start by asking if you can provide profiled RGB in your PDF. That’s becoming the standard for color management, where you export to the default PDF/X-4 preset which exports all RGB with an .icc profile, and includes an expected CMYK output intent without making conversions on export. That workflow should prevent CMYK-to-CMYK conversions, and there would be no TAC problems assuming the printer knows what they are doing.

If they are insisting on all CMYK, but wont provide a profile, you’ll definately want contract proofs, and maybe some test proofing.

CMYK-to-CMYK conversions can be quite bad especially if the source CMYK is a smaller gamut than the destination, i.e. uncoated to coated. If I get CMYK from another source with a wrong profile, I will convert it to my preferred RGB editing space and color correct.

[ukzembla]

Thanks, that's really helpful. I'll try asking if the printers are able to work with RGB in PDF/X-4 for future jobs. I've had other printers send me guidelines that don't mention whether a image files are RGB / CMYK / greyscale, and just ask me to export with "no colour conversion" selected (but PDF standard is "None", not X-4). Which makes me very nervous, as I have no idea why they'd ask for that - presumably they'd be converting later on in the process. It's difficult resorting to forums for advice rather than getting actually helpful info from the printers!…

[rob day]

Which makes me very nervous, as I have no idea why they'd ask for that - presumably they'd be converting later on in the process.

It might be their guidelines are outdated—the old [High Quality Print] preset from CS2 uses No Color Conversion and no Standard. If you include RGB color, the profile Inclusion Policy is important—RGB can’t be correctly converted to CMYK at output without a profile embedded, so the policy should be Include All RGB and Tagged Source Profiles, and if you are using native RGB colors, it should be All Profiles.

You don’t necessarily have to use the X-4 standard—you just need all RGB to include profiles—but there are some benefits, and I doubt a printer would reject a PDF with the X4 standard. X standards include an Output Intent Profile, which is the output profile you expect to be used, but isn’t necessarily the final output profile. Your printer would have the flexibility to use a different profile (to control TAC?) when the RGB images are converted.

Also, X4 doesn’t profile document CMYK colors. Native InDesign CMYK colors export as DeviceCMYK, which make CMYK-to-CMYK conversions of native color less likely—black only text would not convert to 4-color. InDesign native RGB colors always get a profile assignment.

[rob day]

Not sure if this will help, but the interaction between your document’s Color Management Policies and the Export>Output>Color Conversion choice can be tricky.

You can use InDesign’s Separation Preview to see what will happen when you export with the Destination set as Document CMYK, and the Color Conversion set to Convert to Destination (Preserve Numbers).

In order to make it easier to see number changes, I’m placing a PSD filled with 100% Black (0|0|0|100) and 100% Cyan, and saved as a PSD with the US Web Coated SWOP profile embedded:

If I make an InDesign document with Color Settings set to FOGRA52 as the CMYK assignment, and Preserve Embedded (Ignore Linked Profiles) as the CMYK Policy, place the SWOP PSD, and create matching 100%K and 100%Cyan InDesign rectangles; you can see Separation Preview shows the SWOP colors do not change because the policy has ignored the SWOP profile, which conflicts with the InDesign document’s  FOGRA52 assignment:

If I set the Color Settings’ CMYK Policy to Preserve Embedded Profiles, and make a new document, you can see the PSD will get converted to new numbers, but the native InDesign fill numbers do not get converted and remain as 100%K and 100%C:

The Export Convert to Destination (Preserve Numbers) is designed for cases like yours, where you are forced to place CMYK images with wrong profiles, but don’t want your native ID swatches changing. However, to get it to work the document CM Policy has to be set to Preserve Embedded Profiles.

[ukzembla]

Thank you for such a detailed example! That really helps illustrate how things work. I am in fact querying things with the printer, perhaps I'm getting conflicting advice from different people in the production chain... but in any case an example like this is super useful.