Illustrator 2020 - Overprint on image

[Parallele - Studio 2]

I can not check the overprint option on an image (the option is present but inactive). On the vector elements it works. Is there a new way of doing things?

[Ton Frederiks]

"That's not right, i use this way from 15 years!!!"

That is interesting, I just tried it in CS6 and even there the image needs to be embedded for overprint to work.

[Parallele - Studio 2]

Really sorry, I really can not explain it...

This option is available from illustrator 8 (the .psd was not supported at the time, we used the .eps.). The first thing we learn at school was « always link your image ». For a smaller file size and the auto-update when you modify the image source. 

In my file from november 1 saved in illustrator cc 2019, there a potato image .psd linked. As we can see on the screenshot, the potato appears in overprint on the color background, but it is in normal blending mode (not multiply) and the overprint box is inactive and unchecked.

It appears so because when the file was saved in illustrator 2019, the image was linked and overprint activated. Illustrator 2020 understands this option and retains it but it is no longer available for modification (I can even make a color separation from the old file and the overprint of linked images works).

There is inevitably a bug in the new version because I can not edit any more options than I could before.

I sincerely thank you for your support and your time

[Ton Frederiks]

It is strange indeed.

If you could share the Illustrator file with the linked potatoe file, maybe we could find out what is happening.

[Parallele - Studio 2]

I'll ask my boss tomorrow. Can we do it privately?

Thank you !

[Ton Frederiks]

That's ok.

[Parallele - Studio 2 · Accepted solution]

I open file in CS5 and that's right, i can't put overprint on cmyk linked image, but i can on linked grayscale.

The fact the potato is in multiply blending mode but don't see it in the panel because it's a part of a group elements. And the group is not multiply, only the .psd linked image inside the group.

I will go with the Multiply blending mode to keep my images linked. I need to send my files today. 

Thank you so much for your time.

[Ton Frederiks · Accepted solution]

Multiply explains it. Multiply should work similar to Overprint and give no problems with modern rips.