[Scribus] Print preview and its relation to exported PDFs

[Branko Vukelic]

Hi,

I am helping someone test his printing equipment and prepress workflow. He 
thought he could use this image:

http://www.treasurebeach.biz/PGS/Test Image.zip

It is a test RGB image featuring a couple of photos, test charts, and, most 
importantly for this topic, a greyscale gradient along the right edge.

Now, the greyscale is supposed to be composed of colors where R=B=G. In Print 
preview, when I turn off the Black channel the gradient disappears 
completely. That is exactly as I like it (but not as I expected).

When I export to PDF, the situation is exactly as I expected, but not quite 
how I would like it to be. The grey gradient is now composed of CMY colors, 
and the ballance is somewhat towards yellow.

Although I understand that CMS is supposed to break down RGB greys into CMYK 
(therefore grey being separated to all CMYK plates instead of only K) 
wouldn't it be better if there was an option of forcing greys to use only K?

Am I missing something when exporting PDF or this is a whishlist item?

Best regards,

Branko (a.k.a. foxbunny)