[Scribus] Colour management questions

David Purton dcpurton
Wed Dec 1 12:59:50 CET 2004


I'm trying to get colour management working, but I'm sure I'm doing
something obvious wrong, since colours do not look like I expect them

I'll use cyan as an example, but no colours look like what I expect.

I would like the solid colour cyan to look like process cyan, but
instead it seems to look more like the nearest colour you could get in
cmyk to RGB #00FFFF. My best guess is that Scribus does not seem to 
differentiate between RGB and CMYK colours and everything is treated as
RGB and then corrected to the nearest cmyk colour. Is this right, or am
I up the creek? Regardless, how can I get scribus to display cyan so
that it actually looks like process cyan? (Roughly the sort of colour
you get if you export a solid cyan square from scribus to a cmyk pdf.)

The second question is perhaps related. If I create say a filled cmyk
tiff which is just cyan, and also an rgb tif of just rgb #00FFFF and
import both pictures into Scribus, they look the same and again neither
looks like the process cyan colour mentioned above that I want.

Unless I'm really confused, I would have expected the two bitmaps to
look different - the rgb with the nearst approximation to #00FFFF and
the cmyk looking like process cyan.

lcms is working properly, beacuse I get exactly the behaviour I want
using the separate plugin in the gimp. If I separate the rgb file and
then use the separate plugin to view a proof I get an image that looks
reasonably similar to what scribus shows on screen for both the rgb and
cmyk tif. If I create a separated image of 100% cyan in gimp by manually
making up the 4 layers like what the separate plugin does and then get a
proof, I get my process cyan like colour.

So what am I missing in Scribus?

If it helps, I use CorelDRAW at work for prepress work in publishing process
colour textbooks, so all the colours we use a pantone process colour
SWOP guide to choose colours, which look much the same on screen.
(Precise colour control is not necessary for our work, I'm used to
things looking more or less right automagically.)



This is my setup:
liblcms 1.13 & Scribus 1.2cvs on debian/unstable
Activate Colour Management is selected
System Profiles:
        Pictures:      Adobe RGB (1998)
        Solid Colours: Adobe RGB (1998)
        Monitor:       Sony Trinitron Std D93
        Printer:       Euroscale Coated v2
Rendering Intents:
        Monitor:       Relative Colorimetric
        Printer:       Percetual
Simulate Printer on the Screen is checked
Mark Colours our of Gamut is not checked
Use Blackpoint Compensation is checked

David Purton
dcpurton at chariot.net.au
For the eyes of the LORD range throughout the earth to
strengthen those whose hearts are fully committed to him.
                                 2 Chronicles 16:9a
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