let me start quoting the help text:
Preserve Embedded Profiles
Always preserves embedded color profiles when opening files. This is the recommended option for most workflows
because it provides consistent color management. One exception is if you’re concerned about preserving CMYK numbers,
in which case you should select Preserve Numbers (Ignore Linked Profiles) instead.
Preserve Numbers (Ignore Linked Profiles)
This option is available in InDesign and Illustrator for CMYK. Preserves color numbers when opening files and
importing images, but still allows you to use color management to view colors accurately in Adobe applications.
Select this option if you want to use a safe CMYK workflow. In InDesign, you can override this policy on a per-object basis
by choosing Object > Image Color Settings.
Using a safe CMYK workflow
A safe CMYK workflow ensures that CMYK color numbers are preserved all the way to the final output device, as opposed
to being converted by your color management system. This workflow is beneficial if you want to incrementally adopt color
management practices. For example, you can use CMYK profiles to soft-proof and hard-proof documents without the
possibility of unintended color conversions occurring during final output.
Illustrator and InDesign support a safe CMYK workflow by default. As a result, when you open or import a CMYK image with
an embedded profile, the application ignores the profile and preserves the raw color numbers. If you want your application
to adjust color numbers based on an embedded profile, change the CMYK color policy to Preserve Embedded Profiles in the
Color Settings dialog box. You can easily restore the safe CMYK workflow by changing the CMYK color policy back to
Preserve Numbers (Ignore Linked Profiles).
You can override safe CMYK settings when you print a document or save it to Adobe PDF. However, doing so may cause
colors to be reseparated. For example, pure CMYK black objects may be reseparated as rich black. For more information
on color management options for printing and saving PDFs, search in Help.
It seems, InDesign uses despite the synchronization via Bridge Preserve Numbers instead of Preserve Embedded Profile for safety.
Personally, I would use for one project just one CMYK space:
a) convert in Photoshop all images RGB-->CMYK using this profile and embed the profile in each image
b) make document in InDesign with Preserve Numbers
c) export as PDF without profiles, but with output-intent for this profile (PDF-X1a)
InDesign (even CS6) ignores Gray profiles for viewing and doesn't embed them in PDFs, see (1).
IMO, the only accurate workflow is this one:
a) convert images to Grayscale using a "black ink profile" which is derived from the project CMYK space
b) place Grayscale in channel K of otherwise void CMYK file
c) export as PDF as above
Best regards --Gernot Hoffmann
There are a number of differences between ID and PS Color Settings. Preserve Numbers (Ignore Linked Profiles) obviously isn't applicable in Photoshop where a document can only have one profile. ID defaults to Preserve Numbers (Ignore Linked Profiles), which prevents problematic CMYK-to-CMYK conversions on export. So if you want the CMYK policy to be Preserve Embedded in both programs you have to make it the policy in ID and resave the Color Setting.
Seems CS6 now supports Grayscale, which is great
It actually doesn't—there still isn't a grayscale space in ID and incoming grayscale profiles are ignored. With Overprint Preview turned on grayscales are previewed via the document's CMYK profile (so gray value previews match native CMYK-black-only-value previews). With Overprint off, grayscales preview as sGray (2.1 gamma), which is useful if you are designing for screen and will not be printing. In both cases gray values are exported and output unchanged.
CS6 has added support for exporting PDFs as grayscale. You can now choose a gray profile when exporting and convert all color to the chosen gray space.
Thanks for your reply. I'm very familiar with the quoted text. Unfortunately, if one wants to truly practice color management, you can't have applications do what I've described.
When hundreds of files per day are processed, most desirable scenario is for an app to honor both tagged and untagged files.
I hope Adobe can try to accept my critique and offer a truly flexible solution.
Thank you for your reply. Good info about grayscale in ID (or actually, not in ID).
And yes, have to alter ID and IL's color settings to preserve. Unfortunately, still the issue with untagged.
Wishing for Adobe to fix that. Feel they can. Even if most people don't prioritize CM, when done correctly, really helps those of us that do.
Unfortunately, still the issue with untagged.
The Color Management Policies are saved with the document when it is created—the policies are document not application specific. So if the setting was Preserve Numbers (Ignore Linked Profiles) at document creation, CMYK profiles will be ignored until you change the policy. However you can't change the document's policy simply by changing or syncing the Color Settings because all that does is change the policies for future documents.
To change a policy you have to close the doc, set the new policy and check Ask When Opening. When you open the doc you'll get a warning and oppurtunity to change the existing policies.
There's a legitimate argument that CMYK-to-CMYK conversions can create more problems on press than they solve—contaminated primaries, single color blacks converting to 4-color, loss of gamut—that's why Preserve is the default for many settings.