[Scribus] CMYK image processing

Kai-Uwe Behrmann ku.b
Mon Mar 20 07:46:46 CET 2006

Am 20.03.06, 01:07 +0100 schrieb Helmut Wollmersdorfer:

> Kai-Uwe Behrmann wrote:
> [cinepaint 0.20-1]
> > Can you be more specific to fix the problems you have? What are the points 
> > you have with CinePaint's usability? 
> E.g. for conversion into CMYK it should be enough to select
> Image -> Mode -> CMYK
> The necessity to add alpha is a technical solution and not easy usability.

Ok, I will add the alpha automatically. For the -> Cmyk conversion, I 
have the feeling, it should remain a conversion with the options involved 
- rendering intent, bpc, profile selection. Perhaps it is possible to 
introduce a mode there no request is necessary and the conversion performs 
from default values. Have to think how to do it.
> > When did it crash? 
> I do not exactly remember. In my second session it crashed after 
> activating/deactivation some channels.

There where recently fixed some bugs regarding layer handling. Maybe it 
fixes some errors for you. Sorry, the changes are in CVS only by now, but 
should be in the next release.

> > What libtiff version do you use?
> $ tiffinfo
> LIBTIFF, Version 3.8.0
> Copyright (c) 1988-1996 Sam Leffler
> Copyright (c) 1991-1996 Silicon Graphics, Inc.

This one is reportedly buggy. Please update to any later version. I hope 
that the errors will dissappear afterwards. 

> > One possibly reason, which comes to mind is a possibly missing profile 
> > at your RGB.jpg. This is needed before converting. It needs being 
> > attached.
> In my second session (after trying around some time) I was able to 
> convert a RGB.jpg into a CMYK.jpg. But 'save as' tif was not possible - 
> it did not save the file to disk.

Oh this is not tested at all. Cmyk jpeg's are a difficult thing and I dont 
remember talking about it seriously beside it is something existing. Maybe 
I am wrong about this subject. These are just my observation.

> At a next try (fresh start) I opened the CMYK.jpg, it asked for 
> conversion from one CMYK-ICC to another and then looped in throwing 
> errors 'Please add alpha to image before converting'. I had to restart X 
> with cntl-alt-backspace - X was dead. [1]

The error displaying is terrible, you are right.

> > I've put a lot of work into CinePaint's Cmyk capabilities and it is 
> > useable to some extent. 
> > But without feedback it is much harder for me to improove anything.
> Here is the point in this discussion where I should subscribe the 
> developer list of cinepaint. I can take the task of testing.

The adress is here:

> > For debian I cant say much, as I dont do the packages and testing there.
> [1] I will raise a critical bug at Debian-BTS.
> Helmut Wollmersdorfer

I will be happy to work with you on the issues on CinePaint.

Kai-Uwe Behrmann
                                + development for color management 
                                + imaging / panoramas
                                + email: ku.b at gmx.de
                                + http://www.behrmann.name

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