I am on Debian testing/Bookworm and I got updated to GNOME 40.
In editor main window there is a monitor profile selector (lower border of editor window), with a selection of icc profiles and System Default (from GDK), if a default exists.
If I compare “System Default (from GDK)” with “None”, I get the same color output with GNOME 40. In GNOME 38 there was an obvious difference.
If I compare “System default (from GDK)” with “my EIZO monitor profile from calibration” I now see a difference in GNOME 40. In GNOME 38 they were the same. “System default (from GDK)” is my normal setting.
I have selected my “my EIZO monitor profile from calibration” profile in GNOME color management setting, so GNOME is aware of the icc-profile for the monitor.
I have a wide gamut EIZO monitor which I calibrate regularly. Debian 11 Bullseye GNOME 38 was fine. For GNOME 38 “System default (from GDK)” = “my EIZO monitor profile from calibration” (same rendering) in RT editor window and “none” was an obvious un-calibrated state.
Is it so that Debian testing/Bookworm and GNOME 40 is not compatible with RT-git-dev (from source) and RT-5.8 from Debian package? I have tested both and I get the same issue.
EDIT: Debian testing/Bookworm GNOME packages are not all of the same version. But GNOME system info now displays GNOME 40.x. Has anyone else seen this issue of color management/rendering?
I am uncertain as to what has happened. I have been fine for a year on Debian Testing Bullseye + RT-git (from surce) and suddenly it changed when GNOME was updated to GNOME 40.
I wish I could describe the color rendering error in more objective terms.