Here's a Good One...

[Jon Morgan]

Have an InDesign CS3 document with many placed TIFF images that were built from the same background image but have different foreground content. On one of the images, the TAC in parts of the foreground needed to be reduced to satisfy press conditions/requirements, so I:

1. Open the offending image in Photoshop.
2. Sampled a small area of the image that was already well below our TAC threshold and noted the 4-color values.
3. Used Photoshop's "Covert to Profile" function and applied a simple UCR profile and confirmed that the offending areas of the image were now at or below the needed TAC threshold).
4. Re-sampled that same small area of the image and found that the 4-color values did NOT change (which I expected) .
5. Saved the updated TIFF image WITHOUT embedding the UCR profile.
6. Updated the image in InDesign and exported to PDF.
7. Opened the PDF in Acrobat and used the Output Preview function to sample that same small area and found considerable color differences between the image that was UCR'ed and all the rest (remember, all the images have the same background (just different foreground content).

I...
1. Did not embed the UCR profile upon saving the TIFF image.
2. Chose no color conversion and not to include/embed any profiles during the PDF making process.

Why did the color change????!!!!

Perhaps my InDesign color settings are flawed? I've never been able to get a straight answer as to what the correct settings should be for a commercial printer. Perhaps using the "Convert To Profile" feature is not the best way to handle simple color changes like what I did?

Thoughts anyone?

Thanks,
Jon Morgan
Hopkins Printing

[dimitri]

The output preview has an output profile setting, by which it simulates the image. What that profile setting was? Different than the UCR profile? If so, your image might be indeed as you wanted, but the output preview, governed by the above-mentioned setting, would be different.

I think that the best way would be to convert the image to the desired profile, embed the profile, and use that same profile throughout the workflow, so that no conversions to match different profiles are requested by the applications that are part of the workflow, both on their color settings and output/print menus.

[Jon Morgan]

I thought the same thing however the color difference appeared on press as well.

Thanks,
Jon

[Lukas Engqvist]

You are working in a safe CMYK workflow (all data cmyk and no automatic colour management), this is a guess from your comments, but please be explicit if that is correct.

Sampling an area is a strange way, I'd compare the channels in the history. Please go to adobe site and request a more visual TAC warning I have, but this is so clear that you need the TAC warning in PS and not only in InD and Acrobat.

Applied a simple UCR profile? What do you mean? What rendering intent? Black point compensation? I'm perhaps thick but not understanding what you are saying.
Your numbering your steps with two 1's and two 2's isn't really helpfull to me, perhapps it is to others.

Personally I just prefer to work in an RGB workflow, with that wich is to be colour managed, saves me from TAC problems. Sometimes you will have to convert from CMYK to RGB or LAB and then back to CMYK, though there is support for device links in CS4.

[mattbeals]

Originally Posted by Lukas Engqvist

Sometimes you will have to convert from CMYK to RGB or LAB and then back to CMYK, though there is support for device links in CS4.

Which applications support device link profiles directly? I thought it was only PhotoShop that supported device links.

[Lukas Engqvist]

Ye sry, guess I was ambigous PS CS4