[Scribus] Colour management questions

[David Purton]

On Thu, Dec 02, 2004 at 01:16:32PM +0100, Plinnell wrote:
> On Thursday 02 December 2004 13:36, David Purton wrote:
> > Here is a links to an image, that will better explain what I meant in my
> > original email:
> >
> > http://marshwiggle.net/scribus.png
> >
> >
> > cheers
> >
> > dc
> 
> Hi,
> 
> That looks *exactly* like I would expect.
> 

Then we have different expectations. If I specify process cyan, then I
want it to look like process cyan, not RGB #00FFFF converted to CMYK.

RGB #00FFFF is NOT the same as process cyan. They are different colours.
#00FFFF can not be represented in CMYK, as I'm sure you know.

This is why I asked the question in my first email: Does scribus
differentiate between RGB and CMYK colours or are all colours treated as
RGB?

Here's a demonstration of the difference in RGB and CMYK from CorelDRAW
12 under winxp:

http://marshwiggle.net/corel12.png (screen shot not export)

Note that this looks very similar to the two gimp pictures in the
scribus image above.

If import the two tiffs (one in RGB, the other in CMYK) into Corel12
they also look like this picture.

Here are some similar ones created in Corel:

http://marshwiggle.net/RGB.tif
http://marshwiggle.net/CMYK.tif

These should look different when imported into scribus with colour
management enabled. Without colour management, they should look the
same.

> One very important point, GIMP while it can generate CMYK separated TIFF's, 
> cannot yet display accurately for the gamut compression in the conversion 
> from > RGB > CMYK Euroscale. The current Color Management while it uses 
> littlecms, does not yet have all the pieces. So opening a CMYK TIFF in GIMP 
> is not really showing what really is going to print to CMYK.

I know this. I did not open a CMYK tiff in the gimp. I created a four
layer image and manually made each layer with a small rectangle of 100%
process color. Then I saved this as a cmyk tiff using the separate
plugin. I could achieve exactly the same result using any other image
app that supports a true cmyk colourspace.


I do not think monitor profiles are causing the difference.

[snip stuff on monitor profiles]


cheers

dc


-- 
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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