Created attachment 193797 [details] The ICC profile for my laptop display DESCRIPTION After I updated from 6.6.5 to 6.7.1, there was a noticable yellowish tint when I used an ICC profile for my laptop display. Using manual downgrade I found out that the regression started happening on 6.6.90 version. Git bisect lead me to this: ``` git bisect bad 84a4451685055cfe00e682a9b9436c54c24f01fc # first bad commit: [84a4451685055cfe00e682a9b9436c54c24f01fc] opengl,backends/drm: apply MHC2 ICC profiles more correctly ``` STEPS TO REPRODUCE 1. Apply the ICC profile provided 2. Notice the yellowish tint on 6.6.90 or later OBSERVED RESULT Incorrect colors, yellowish tint EXPECTED RESULT Correct colors, without the yellow tint SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.7.1 KDE Frameworks Version: 6.27.0 Qt Version: 6.11.1 Kernel Version: 7.0.10-zen1-1-zen (64-bit) Graphics Platform: Wayland Processors: 16 × AMD Ryzen 7 6800HS with Radeon Graphics Memory: 16 GiB of RAM (14.9 GiB usable) Graphics Processor: AMD Radeon 680M ADDITIONAL INFORMATION Since Bugzilla doesn't seem to let me upload multiple attachments in one go, full git bisect and image comparison will be appended in replies.
Created attachment 193798 [details] Full Git Bisect log
Created attachment 193799 [details] Camera capture of the display, with no ICC applied
Created attachment 193800 [details] Camera capture of the display, with the ICC applied on 6.6.5 (correctly)
Created attachment 193801 [details] Camera capture of the display, with the ICC applied on 6.6.90 and later (wrong, yellow tint)
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/9490
*** Bug 521374 has been marked as a duplicate of this bug. ***
Git commit f7c863a1d72c3a362600458f162ac44793de9385 by Xaver Hugl. Committed on 30/06/2026 at 10:41. Pushed by zamundaaa into branch 'master'. backends/drm: fix SDR MHC2 profiles with a calibration matrix The documentation said that > Target RGB is defined as the encoding used when transmitting colors over the > display wire; typically BT.709 or BT.2020 primaries. which seems to be misleading. If BT.709 is used as the wire format in SDR mode, that leads to wrong results with some MHC2 ICC profiles. M +1 -1 src/backends/drm/drm_output.cpp https://invent.kde.org/plasma/kwin/-/commit/f7c863a1d72c3a362600458f162ac44793de9385
Git commit 280468c491c1b7ff5ef48406e4df465cfe330367 by Xaver Hugl. Committed on 30/06/2026 at 11:10. Pushed by zamundaaa into branch 'Plasma/6.7'. backends/drm: fix SDR MHC2 profiles with a calibration matrix The documentation said that > Target RGB is defined as the encoding used when transmitting colors over the > display wire; typically BT.709 or BT.2020 primaries. which seems to be misleading. If BT.709 is used as the wire format in SDR mode, that leads to wrong results with some MHC2 ICC profiles. (cherry picked from commit f7c863a1d72c3a362600458f162ac44793de9385) M +1 -1 src/backends/drm/drm_output.cpp https://invent.kde.org/plasma/kwin/-/commit/280468c491c1b7ff5ef48406e4df465cfe330367