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View Full Version : pictures in Dot gain 15% result in colored print



sebastian-e-dox
11-23-2012, 02:18 AM
Hey Guys!

We have the issue on a Xerox 560 (no other machine tested) with EX560 (1.0_sp1) Fiery.
The problem ist that it prints pictures that have Dot Gain 15% as ICC profile attached colored. And this happens allthough Grey and Blackprocessing is enabled for CMYK (text,graphics and pictures).

So in my understanding the gray and black values should be kept and printed as pure black.

If I convert the picture to gray every thing is fine as expected.

Why doesnt it work for Dot Gain 15% (which has Gray as alternate color space)? If someone wants to see the PDF please PM me.

TomG
12-12-2012, 03:33 AM
I just figured it out. When you are printing using these settings (I'll try to translate the labels from the German driver):

Color: [x] Black detection
Color expert settings > Source > [x] Honour embedded profiles
Color expert settings > Black & gray processing > CMYK: text/graphics/images

...then the result is a color print.

If you disable to honour embedded profiles then the result is a black print.

But why?

The only content in the PDF document one gray image (1 channel, 8 bits, attached ICC profile 15% dot gain) on one page. The document's output intent is Coated FOGRA27 (Adobe-specific, not ISO!) <- but this shouldn't have an effect.

The checkbox that "honors embedded profiles" (if present) should make the color server to look for an attached ICC profile at each object. In this case there's only one object (gray image). The color server therefore should detect the ICC profile dot gain 15% and use it as source profile, right? The color transformation then will be from source to destination profile, we're using Fiery's default 90gsm profile BUT with black detection and gray protection.

It seems that black detection and gray protextion is overridden when using "honor embedded profiles". I don't have any other explanation...

Can anybody explain this beaviour and tell if this sould work like this or if this is a bug?

Btw here you can download a test file: http://www.file-upload.net/download-6918213/text1.pdf.html