Use PDF x4 for the pdf standard.
Tagged PDF is about putting structure on the contents - so the PDF has information on sections, captions, headers, paragraphs. Used for accessibility and text extraction. Very, very complicated, but happily nothing at all to do with colour or profiles.
Thanks Eugene, i'll do that.
PDF x4 was not the solution. It doesn't retain the profile embedded to an CMYK image. When I check the pdf file with Pitstop, there is none profile in the CMYK image.
My goal here is to have embedded CMYK profiles (could be different ones) in the images and then in a prepress system convert both RGB and CMYK images with a desired destination profile. The embedded profiles would act here as source profiles.
What I'm wondering is, why doesn't InDesign work according to the way in the following description:
Profile Inclusion Policy: Include RGB And Tagged Source CMYK Profiles
Description: Includes tagged RGB profiles and Document RGB profiles for untaaged RGB content. Also includes profiles for tagged CMYK (i.e. placed objects with embedded profiles). CMYK colors from native objects (and from placed objects that don't have an embedded profile) are left uncalibrated.
It should preserve them as PDFx4 is designed for that.
I'll wait for Rob Day to pop along as he's a lot more familiar with colour profiling and this kind of work.
If you choose Include All RGB and Tagged Source CMYK Profiles any placed CMYK objects that have profiles that match the document's CMYK profile are considered Device CMYK, and no conversion is necessary at output. So in this PDF I have the same image profiled with the document's GRACol CMYK profile (top) and US Newsprint (bottom). Acrobat's Output Preview tells me that the top image is Device CMYK (it matches the PDF/X Output Intent) and the bottom image has the US Newsprint profile:
The bottom image sampled
But with that setting also native CMYK elements like text will be tagged with a profile, and that I do not want to have.
If you don't use the PDF/X-4 standard and change the output to Include All Profiles then all color including native ID colors gets profiled. In that case my top image would have the GRACol profile and as you noted any native colors would also be profiled.
I'm not following why placed image color should be profiled, but a native ID color shouldn't?