[Scribus] [announce] CMYK Patch gets image support

[David Purton]

On Sat, Feb 12, 2005 at 09:57:14PM +0100, Martin Costabel wrote:
> David Purton wrote:
> >Hi folks,
> >
> >I finally uploaded a first up attempt at getting CMYK images working.
> >
> >http://marshwiggle.net/scribus/
> >
> >There is a tarball containing test files and what I say is the "correct"
> >output for comparison. 
> 
> Sorry for coming late into this discussion. I also apologize for not 
> knowing anything about color management, profiles and such things.
> 
> But I have the suspicion that the participants in this discussion are 
> all using little-endian systems, so my experiences with the patch on the 
> bigendian MacOSX/Fink version of scribus might be useful. In short: they 
> are not pretty.

I'm not at all surprised. I have had no experience in working with
big-endian machines. And had already raised this a potential issue.

If it's not too much trouble, can you create corresponding pdfs for each
of the pdf files in cmyk-patch-test.tar.bz2 with the patched version you
are using? I'll look at things and make corrections.

> 
> I have looked at the files in cmyk-patch-test.tar.bz2 and I am seeing 
> the following:
> 
> A. On unpatched scribus-1.2.1 with standard rgb and cmyk profiles:
> 
> 1. If I open a new document and either import cmyk.eps or create picture 
> frames and load any one of cmyk.eps, cmyk.tif, or rgb.tif, I get 4 
> absolutely identical results, except that the imported cmyk.eps shows 
> white vertical separation lines in the middle of the squares.

Interesting. I never got identical results with an unpatched Scribus
unless colour management was disabled or not compiled in. Are any colour
transforms being done? Are the colours in Scribus different to the ones
you get if you open rgb.tif in any image viewer?

> The 
> printer preview looks also almost the same. The colors are not identical 
> to any of the cases in the screen.pdf or printer.pdf files, they are 
> somehow "brighter".

Ah - There is is no colour management done in print preview. I suspect
that colour management is not enabled or compiled in in your build. Can
you check this?

> 2. If I open the cmyk.sla file, the last 3 cases where files are said to 
> be loaded into picture frames, look identical but very different from 
> case 1, but the first series that is said to correspond to imported 
> cmyk.eps looks completely wrong: For example the first square that 
> should show two shades of cyan, has a cyan half and a red half and so 
> on, all squares show two different colors in the two halves.
> 
> B. On a patched scribus-1.2.1.cvs:
> 
> 1. In a new document, the imported cmyk.eps, the picture frames with 
> loaded cmyk.eps and with rgb.tif still look identical and almost 
> identical to the unpatched case A.

This would be expected if colour management was disabled.

> However, the picture frame with 
> loaded cmyk.tif is completely wrong: Yellow becomes magenta, black 
> becomes cyan, whereas cyan, magenta, red and green in the first row and 
> blue in the second row all become white.

This is almost certainly a bug in my code. If you indeed do not have
colour management enabled, then this one should look identical to the
other three.

> 2. If I open the file cmyk.sla, the first series (imported cmyk.eps) 
> looks for the first time similar to what it should, namely every square 
> shows two shades of the same color.

mmm ok, this would argue, that colour management is working, but perhaps
you had it disabled in your above tests?

> The other 3 series show different 
> behaviors: The cmyk.eps and rgb.tif look almost like they did in A1, but 
> the cmyk.tif has blue instead of light brown, red instead of black and 
> black instead of red, and various shades of green instead of cyan, 
> magenta and blue.
> 

Again, this is a bug in my code.


Creating corresponding pdfs of the one in my test suite would be
helpful.

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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