[Scribus] CM problem printing with ICC profile (RGB vs. CMYK?)
Sat Oct 23 14:54:40 CEST 2004
Ok, so perhaps not too many people doing color-managed printing with RGB
inkjets on the list? I've continued working with the problem, and I think
ther is a bug if the following assumption is true:
Printing an image to a file in Scribus with an output ICC profile should
generate a result that looks the same on the screen as applying the output
profile to the image directly.
Here's the details:
> demo. Unfortunately, using the profile to print images from Scribus doesn't
> work nearly so well, producing a strong blue cast.
* I'm now using Scribus Version 1.2.1cvs (22-23 October 2004)
* I see the same result printing to a postscript file.
* here's a test any Scribus user can try without my profiles:
- grab an image, I've been using the target .jpg from http://www.targets.coloraid.de/
- grab an RGB output profile. I went to www.epson.com, clicked 'USA',
then put 'ICC profile' into the search box, selected 'Within Support',
did the search. First result is "1440 and 2880 ICC Profiles for
ColorLife Paper", which I followed to get epson10027.exe. You can
use 'unzip' on Linux to get the ICM profile out (long name SP...ICM).
- set this as your printer profile, sRGB as your input profile, set
printer intent to 'Perceptual', put your image on the page, print to
file with "Apply ICC Profiles" under "Advanced Options..." checked.
- back to the command prompt, use jpegicc from the LCMS tools to do what
should be the same thing to generate a jpeg file. Something like:
% jpegicc -i sRGB.icm -o SP...ICM -t0 -q100 infile.jpg outfile.jpg
- compare outfile.jpg with the postscript printed output.
On my system these look quite different, but using -t3 (Absolute
Colorimetric) with jpegicc generates something closer to the Scribus
output. I -think- they should look the same (with jpegicc -t0), but I am
still only a student of color management.
In answer to an earlier question from me, RGB printer profiles should work
because util.cpp:LoadPictCol() checks the printer profile color space and
creates the appropriate transform (RGB-RGB or RGB-CMYK) according to the
result. The cmsCreateTransform() call is using the correct IntentPrinter
value when it is called in this routine.
So, please, can someone else have a look at this, perhaps confirm the
result, and explain whether this is/isn't the way it is supposed to work?
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