[Scribus] Color Management issues

[jon]

I don't know if any one else answered any of your requests and I can 
say nothing
to issues with scribus but I may have some notes to CM.

> Hi there,
>
> this week, I've come across a color management issue with Scribus. I'm
> using 1.3.3.7 on Linux (thanks to mrdocs for the SuSE RPMs!).
>
> I'm using sRGB as the source profile and EuroscaleCoated as

sRGB is not a good source to convert from. It's colorspace is very 
limited and furthermore
it's whitepoint is 6500? K wich is not suitable to convert to Euroscale 
(5000?K).
The whitepoint shift might be or is to harsh to preserve colors intents.

If you want to have better results you should convert any rgb to say 
Adobe RGB (6500?K - but rel. large scale color space)
or much better ECI rgb (5000?K, large scale). This is for Europe only, 
though.

Euroscale Coated is an commonly used but very old and out-of-standard 
profile.
You might get much better results with the rel. new ISOcoated (ECI) or 
according, depending on what kind of paper or
printing process you want to use.

> printer/destination profile. Now if I include an RGB picture into
> Scribus and produce a CMYK PDF (Printer target), the picture comes out
> different than when I convert the RGB picture to CMYK with embedded
> EuroscaleCoated profile using tifficc. The picture converted by Scribus
> looked greenish (there were mostly yellow/orangish colors in the 
> picture).

Seems that Scribus doesn't do correct whitepoint shifting? Try 
converting all rgb to ECI, resp. 5000?K, before.
Or the sRGB (source) profile isn't correctly embedded or read out.

> I can provide test SLAs and images, if there is a need to.
>
> I supposed that embedding an image into a Scribus document, then
> exporting to PDF with Printer target, should produce the same result as
> converting to CMYK first, then exporting.
>
> I used "tifficc -i sRGB.icc -o EuroscaleCoated.icc -t1 -b -c2 -e" for 
> the
> conversion which should be equivalent to setting all rendering intents
> in Scribus to "Relative Colorimetric" and using the same profiles.

I am not quite sure, there def. is more than one correct way to 
transform and shift whitepoints.
But with photographic images I commonly get the best results when using 
perceptual as rendering intend instead of relative shift (rel. 
colormetric).

Jon