Converting RGB bitmap to CMYK, colour profiles

My question is related to this one:
What’s the point of converting RGB images to CMYK TIF/TIFF before placing them in InDesign?

I am preparing some artwork in Illustrator, which contains some bitmaps created in Photoshop.

The printer has asked for PDF format, 300dpi CMYK with ‘no embedded colour profile’.

I am unsure of the best workflow. I had assumed I should convert my bitmaps from RGB -> CMYK in Photoshop and save as TIFF, then place that in Illustrator. But when changing colour mode Photoshop asks which colour profile to use and I believe that profile is then embedded in the TIFF.

Reading the answers to question linked above it sounds like I would be best to instead leave my bitmap artwork as RGB, place it in Illustrator and just export the PDF… then at point of printing (i.e not by me) the conversion from RGB->CMYK using most appropriate profile would be done.

From what I have read there is also the possibility to place RGB artwork in Illustrator but export the PDF as CMYK, but presumably this means using a particular colour profile… which would then be embedded in the PDF?

It is hard to reconcile with what the printer has asked for, possibly I am misunderstanding.

Either way I should obviously attempt to preview my RGB bitmaps as CMYK beforehand of course.

Answer

I’m not a CMYK master by any means, but I’ve dealt with enough third-party printers to have heard this come up several times in the past. Any press operators out there who have better info that this, I welcome it.

Your printer is leaving a piece of the puzzle out. As you’ve discovered, you can’t convert to CMYK without converting to a specific CMYK color profile. From that point, you can untag the image by assigning ‘no profile’, so the profile is not embedded.

Maybe your printer doesn’t want that profile embedded (why, I don’t know – profiles take up very little space, and at worst they properly define color appearance, which is the whole point of color management). Your printer needs to either tell you what specific profile to convert to, or allow you to submit RGB files in either AdobeRGB or sRGB, and handle the conversion on their end. And either way, I hope you’ll be able to see a printed proof before the final run, because with this kind of instruction from the printer, I’d be wary of the results.

If they do tell you which CMYK profile to use, previewing your bitmaps in that space while making final adjustments will definitely help keep color where you want it when converting.

Attribution
Source : Link , Question Author : Anentropic , Answer Author : digijim

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