[Libreoffice-ux-advise] [Bug 72146] CMYK conversion incorrect? RGB does not match. Missing color profile?

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=72146

V Stuart Foote <vstuart.foote at utsa.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vstuart.foote at utsa.edu
          Component|UI                          |filters and storage
                 OS|Mac OS X (All)              |All

--- Comment #19 from V Stuart Foote <vstuart.foote at utsa.edu> ---
This really is an import filter issue, not about working in CMYK which as noted
we can't do, and on export to PDF we specify the sRGB.icc (comment 4). Frankly
for UX the CMYK on the color picker is not very useful and should probably be
dropped--I think that was gist of comment 2.

So, this is mostly about the graphics filter mishandling CMYK colorspace images
on insert into a sRGB color space, with poor results.  

For what it is worth, the ImagMagick 'convert' utility done without a -profile
spec produces the same sRGB hue as LibreOffice's existing import.

IIUC, a source image will often identify its color profile, and some image
formats will fully embed it.  So thinking out loud, while filter inserting a
CMYK color space image, could we pull out the color profile if specified, and
if one of the "well known" ICC profiles, e.g. supporting PDF/A-1, then use that
to control import conversion of the image to our sRGB.icc compliant color
space?

=-ref-=
http://www.color.org/chardata/drsection1.xalter

http://www.color.org/srgbprofiles.xalter

http://www.imagemagick.org/Usage/formats/#profiles

https://www.pdfa.org/wp-content/until2016_uploads/2011/08/tn0002_color_in_pdfa-1_2008-03-14.pdf

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