[Scribus] cmyk vs rgb

[Farid Elyahyaoui]

I sent this one with attachments but It didn't get through.
So here it is without attachment.
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I'm still trying to grasp the color management settings in scribus
(and color management in general). I understand that RGB and CMYK are
completely different color spaces. What I fail to understand is the
following though:
If I load a RGB jpeg into scribus and output a cmyk pdf and view the
pdf on the same machine with acrobat reader the colors look greyish. I
understand that I need color management to get matching colors between
screen and what gets printed on paper.

BUT (!) why do I get the different colors if I only work on one
monitor on one machine?

One would expect that if scribus calculates RGB->CMYK and acrobat
displays these CMYK colors on the monitor (using RGB of course) that
the colors would be the same. that is if the calculations are the
inverse of each other. Or am I completely wrong here?