Currently by default GIMP-2.10 and GIMP-2.99 can’t correctly use ArgyllCMS XYZ LUT monitor profiles.
The problem is that these monitor profiles have an embedded matrix. By default this matrix uses the sRGB color space primaries, but with swapped RGB channels. The point of the embedded matrix with the swapped channels is to alert people to the fact that software is failing to actually use the XYZ LUT.
Indeed GIMP - or rather babl - is failing to use the XYZ LUT. Somehow babl code is detecting and using the matrix instead of using the LookUp Tables. So colors are swapped. Red becomes green and so on. Bug reports have been filed (see below).
I’m under the impression that DisplayCAL, which uses ArgyllCMS to make monitor profiles, does make an XYZ monitor profile by default. And perhaps GNOME color manager or related software also does. So even if you didn’t deliberately ask to have this type of monitor profile made, it might be what you are using.
So if you are using GIMP-2.10 or 2.99, and you see very strange colors when trying to use your monitor profile, check to see what type of profile it is. If it’s an XYZ LUT monitor profile, there are two workarounds:
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Start GIMP by specifying to disable the babl transforms. I don’t know how one would do this on Windows, but on Linux the command looks like this:
GIMP_COLOR_TRANSFORM_DISABLE_BABL=yes /path/to/gimp-executable/gimp-2.xx
where of course “gimp-2.xx” is either gimp-2.10 or gimp-2.99.
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Use a different type of monitor profile. A shaper matrix profile is a good type of profile to use for many monitors.
For details on how babl currently deals with XYZ LUT profiles, go here:
https://gitlab.gnome.org/GNOME/gimp/issues/2025
and here:
https://gitlab.gnome.org/GNOME/babl/issues/21
Based on the (currently as I write) most recent comments in the bug reports, it’s not clear:
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whether the way babl handles XYZ LUT profiles with embedded swapped color matrix profiles will ever change to avoid producing totally wrong colors . . .
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or whether GIMP users instead will have to avoid using XYZ LUT profiles made using ArgyllCMS . . .
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or whether perhaps ArgyllCMS could add an option to not embed the matrix, which option people making XYZ LUT monitor profiles for use with GIMP would have to use . . .
A related question is whether DisplayCAL or GNOME color manager-related software should make XYZ LUT profiles by default, if indeed they do. GIMP is not the only software that can’t use this type of profile, and often people who use GUI software to make ICC profiles rely on default settings.