: Illustrator/InDD - Grayscale layers combine to CMYK Problem I have a grayscale eps image that is throwing CMYK errors with Acrobat preflight. Output Preview show no CMY values - only K, but

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Posted in: #AdobeIllustrator #AdobeIndesign #Cmyk #Grayscale

Problem

I have a grayscale eps image that is throwing CMYK errors with Acrobat preflight. Output Preview show no CMY values - only K, but the preflight errors will cause problems when we send it to the printer.

Setup


I have a Illustrator EPS file that has three layers: text, lines, wave graphic.
That EPS file is placed in an InDesign file
That InDesign File is exported with set Adobe PDF preset (print - with crops - technically prints for CMYK, but should leave colors alone since everything is black - 100s of other images are fine. Changing to no conversion doesn't help)
Open that PDF file in Acrobat and run Digital Printing B&W and the image comes back with "Document Images on CMY plates" (14 instances in the image)


History of things that didn't work


First step was to select everything in Illustrator and convert to grayscale.
Originally the wave graphic was an embeded bitmap. Suspecting this was a problem I unembeded it to a tiff file, converted that to grayscale
Since that layer has to show the one below I needed a way to get a transparency. Eventually (magic??) I ended up with the wave as a PSD file (in Photoshop) with a transparent background - which I then selected and copied into the original EPS file. It is now an embeded TIFF image.
Created a new EPS file and copied the stuff over into it.
The lines were CMYK gray - converted to grayscale 80%
Text is black. But just to be sure I selected it all and made sure it was grayscale black.
Appearance of Black: Both ID and IL were set to rich black. I switched to output accurate black (and did another "convert to grayscale" to get a changed image to update the link in ID). Still triggering the CMYK preflight error.


Interesting things


There are three layers, if I hide two layers and save with the third visible there are no problems in the preflight. If I display the wave and the lines (lines go behind the wave image) - then the CMYK error comes up.
Output Preview show no CMY values - only K
When you go to "show" the errors it outlines random square patches of the image.




Why EPS?
Unknown why the original choice was made, but it's part of the workflow and cannot be changed (we are talking thousands of images)

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