[Gimp-user] GIMP-2.10 and GIMP2.99 are still sRGB-only image editors



A misconception I keep seeing on various forums needs to be corrected:

GIMP-2.10 does *NOT* produce correct editing results in color spaces other than sRGB. Neither does GIMP-2.99.

Editing in AdobeRGB, ProPhotoRGB, Rec2020, etc WILL produce *wrong* results for many operations, and unless you are thoroughly conversant with the underlying code, or else have a way to compare results with a properly color-managed editing application, you don't have any way to know what's right and what's wrong. It's best to stick with editing only in GIMP's built-in sRGB color spaces.

The same is true if you are using GIMP-2.99: Some things that don't work in GIMP-2.10, do work in GIMP-2.99. Other things that actually do work in GIMP-2.10, don't work in GIMP-2.99.

About two years ago major changes were made in babl and additional changes were made in GIMP-2.99, messing up stuff that still works in GIMP-2.10. For awhile progress was being made in GIMP-2.99 on extending the arena of "what actually works", some of which progress is from bug reports I filed and in some cases helped to fix - it seems nobody else was testing the new code to see what actually did work.

I was able to write code that fixed some of the bugs I reported for GIMP-2.99 color management. But once I reached the point where further coding requirements exceeded my coding ability, progress simply stopped, with everyone else saying "some day" proper color management for GIMP would be a priority. I began to feel like the best way to make sure a bug would never get fixed, was to have the dreaded "Concepts: Color Science" tag attached to it.

Since autumm of 2013 I've been participating in GIMP development, mostly in the area of color management (editing in color spaces other than sRGB) and color science (making sure GIMP code produces correct results for things like layer blend modes, Curves and Levels, AutoStretch, Luminance, and so on; and adding code for things like LCh color pickers and blend modes).

Participating in GIMP development used to be challenging and enjoyable. But over the last couple of years my interest in and patience with the slow pace of progress regarding GIMP color management have dwindled to the point of disappearing altogether.

If someone else feels like helping with GIMP color management and color science, here's a list of still-open bug reports that I reported after the migration to gitlab, most of which have to do with color management/color science:

https://gitlab.gnome.org/GNOME/gimp/-/issues?scope=all&utf8=%E2%9C%93&state=opened&author_username=ellestone

Here are bugs that I opened before the migration to gitlab:
https://gitlab.gnome.org/GNOME/gimp/-/issues?scope=all&utf8=%E2%9C%93&state=opened&author_username=bugzilla-migration&search=ellestone

The most important color management bugs still open from before the migration to gitlab are these:

* Replace hard-coded sRGB parameters to allow editing in other RGB working spaces (opened 6 years ago): https://gitlab.gnome.org/GNOME/gimp/-/issues/594 - in some ways this bug is obsolete as current GIMP color management issues are less about actual hard-coded values and more about a lack of any way to convey the required "not sRGB" color space information to various sections of code that need this information.

* Decomposed to LAB images have the wrong ICC profile assigned (opened 4 years ago): https://gitlab.gnome.org/GNOME/gimp/-/issues/883

* Address various limitations of LCMS soft proofing (opened 4 years ago): https://gitlab.gnome.org/GNOME/gimp/-/issues/976
the
and hoping very much that GIMP will find new developers that them a lot of energy and some interest and expertise in color management and color science. * Support for high bit depth RGB (and LCH?) color palettes for painting (opened 2 years ago): https://gitlab.gnome.org/GNOME/gimp/-/issues/1328

Similar searchs in https://gitlab.gnome.org/GNOME/gegl/ and https://gitlab.gnome.org/GNOME/babl/ will turn up a few additional color management issues.

Best of luck to all,
Elle Stone

--
https://ninedegreesbelow.com
Color management and free/libre photography


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