Hello:
While I wait on the phone for Adobe support (+60 minutes now) I thought I'd post here to see if anyone in the community had any feedback on this topic.
We recently discovered that objects created with an RGB build but set to overprint in InDesign will end up as KO type in an exported PDF file. I'm trying to find out if this is the expected behavior or if this is some type of bug in CS6. This even ocurs when all colors must be converted to CMYK or spot color, such as when exporting to X1a.
From a technical standpont, RGB objects set to overprint are tagged with 'OPM 0' and CMYK objects are tagged as 'OPM 1'
From our Enfocus resources:
There are two “overprint modes”:
- Standard overprint mode, also known as “OPM 0”
- Illustrator overprint mode, also known as “OPM 1” or “nonzero overprint mode”
The difference between both modes lies in the effect of the tint value 0 for one of the CMYK inks:
- In standard overprint mode (OPM 0), the tint value 0 of one of the CMYK inks in the foreground object has a knockout effect on the color rendering of the underlying object. In other words, a foreground ink with a C, M, Y or K value of 0 % erases the corresponding background ink. Here, the “foreground inks win” principle applies.
- In Illustrator overprint mode (OPM 1), the tint value 0 is neutral: it is ignored (as if it were “not specified”) and has therefore no effect on the color rendering of the underlying object.