I am having difficulty maintaining correct color when combining RGB and CMYK artwork on an InDesign artboard when transparency is applied.
Our workflow subscribes to a "late binding" methodology, where RGB and CMYK artwork are tagged with the correct ICC profiles upstream and final color conversions occur at the RIP. When RGB and CMYK artwork (without transparency) are included on the same InDesign artboard, the resulting PDF and print both present with expected color.
If artwork with transparency is introduced to the same artboard, the Transparency Blending Space is invoked, and we will experience a color shift in some of our imagery.
If the Document CMYK blending space is selected, our CMYK artwork with transparency maintains correct color, but our non-transparent RGB images appear to be converted to CMYK. We observe this conversion happening when the transparent object is placed on the artboard in InDesign, and it is consistent in the PDF and printed output.
If the Document RGB blending space is selected, our RGB images maintain correct color, but our CMYK artwork with transparency appears to be converted and loses detail.
Examples assume Adobe RGB, and CMYK SWOP color spaces only, and we do not wish to convert all imagery to one color mode before placement in InDesign.
Has anyone experienced this challenge, and have you developed a solution for maintaining correct color in all imagery?
Late binding has its advantages, to be sure, but as you are discovering, it leaves something to be desired. So much is dependent on the software, RIP, color mode, etc. In fact, if you place an RGB image into Indesign and let it convert to CMYK, it is not totally unusual to get a different result from converting to CMYK in Photoshop, then placing that image in Indesign. I know, it's not supposed to work that way.
For my money, I trust Photoshop more than I do Indesign or Illustrator, at least when it comes to handling color, color conversions, etc. Besides, when converting to CMYK in Photoshop, I have the ability to tweak the CMYK file after conversion to be sure I get the best possible dynamic range and color possible. When converting from RGB to CMYK in Indesign, you get what you get, period.
For these reasons, my preference is to place only CMYK images in Indesign, preferably in the same color space, though I am happy to adjust rendering intent from image to image (soft proofed in Photoshop, of course). I never mix RGB and CMYK files in the same document (at least if it is destined for press). I might consider an all RGB workflow, but not a mix of RGB and CMYK. To me, there are just too many things that can go wrong (including the transparency blend space). Maybe they'll work it out so it is perfect one day, but IMO, we aren't there yet. I guess it depends on how demanding the client is when it comes to color, density and gray balance.