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Bug 626944 - Decompose/Recompose LAB use wrong colorspace/gamma
Decompose/Recompose LAB use wrong colorspace/gamma
Status: RESOLVED OBSOLETE
Product: GIMP
Classification: Other
Component: Plugins
git master
Other All
: Normal minor
: ---
Assigned To: GIMP Bugs
GIMP Bugs
Depends on:
Blocks:
 
 
Reported: 2010-08-14 17:31 UTC by Rupert Weber
Modified: 2015-05-02 17:53 UTC
See Also:
GNOME target: ---
GNOME version: ---


Attachments
LAB decompose/recompose w/ new libgimp L*a*b conversions (6.05 KB, patch)
2010-08-14 17:32 UTC, Rupert Weber
needs-work Details | Review

Description Rupert Weber 2010-08-14 17:31:31 UTC
As already discussed on the mailing list, the Decompose/Recompose plug-in ignores gamma and uses a wrong conversion matrix: PAL/SECAM RGB instead of sRGB.

I am posting a patch, but that patch does *not* work with current git master, rather it needs the "libgimpcolor-new-L-a-b-and-L-C-H-conversions-v3" patch posted at
   https://bugzilla.gnome.org/show_bug.cgi?id=325564

So basically I'm posting this here as a smaller testbed for the new libgimp routines.
Comment 1 Rupert Weber 2010-08-14 17:32:49 UTC
Created attachment 167878 [details] [review]
LAB decompose/recompose w/ new libgimp L*a*b conversions
Comment 2 yahvuu 2010-08-18 17:58:53 UTC
A reminder that the decompose/compose plug-ins don't live up to their promise anymore is certainly a good thing. 

However, in contrast to the 'color' layer modes recently under discussion on the mailing list, these two plug-ins should deliver what they promise with scientific rigor -- that is, they need to be fully color-managed and pay attention to the current color profile.

Besides, backwards compatibility suggests to leave the old wrong functions untouched and add new correct ones instead.


Another option to test-drive the new libgimp functions would be create a new plug-in which provides correct conversions under the explicit precondition that the working color space is sRGB. This plug-in surely won't make it into core GIMP, though.

Everything IMHO, as always
Comment 3 Sven Neumann 2010-08-22 19:43:49 UTC
Review of attachment 167878 [details] [review]:

The plug-in should be changed to use the pixel format conversions from babl.
Comment 4 Michael Natterer 2015-05-02 17:53:44 UTC
compose and decompose have been ported to gegl/babl, so this bug is completely
out of date. If there are still issues with the new code, please file a
new bug.