At 32f, linear precision, converting to the monitor profile produces wrong results
Submitted by Elle Stone
In "Preferences/Color Management" select a monitor profile from disk, and make sure Color Management is enabled. Also make sure "Try to use the system monitor profile" is not checked.
Open an sRGB image, make sure the GIMP built-in sRGB profile is assigned, change the precision to "32-bit floating point/linear precision", and convert the image to the monitor profile that was selected in Preferences. The resulting image looks like it was given an approximately gamma=2.2 "correction" somewhere in the conversion process - in other words, the sRGB TRC was somehow misapplied during the conversion.
I tested this with two actual monitor profiles selected from disk, and also with an sRGB profile from disk selected as the monitor profile.
If the precision is "32f/gamma precision", the conversion to the monitor profile is done correctly. I didn't check lower bit depths.
I also didn't check what happens when "Try to use the system monitor profile" is checked in Preferences.
When converting to a monitor profile that isn't the monitor profile selected in Preferences, there is no problem.
The same problem obtains for images that aren't in the GIMP built-in sRGB color space. For example, open an image in the AdobeRGB1998 color space, change the precision to "32f/linear", and convert to the monitor profile selected in Preferences.
Converting an image to the user-selected monitor profile is not a common thing for a user to do (well, except for users who are using an sRGB profile from disk as their monitor profile), but still it should be possible to do correctly, regardless of the image precision.
This bug predates the new babl icc code, and happens regardless of whether the new babl icc code is enabled or is disabled using GIMP_COLOR_TRANSFORM_DISABLE_BABL=yes export GIMP_COLOR_TRANSFORM_DISABLE_BABL
Version: git master