https://bugs.kde.org/show_bug.cgi?id=516639
Bug ID: 516639
Summary: Incorrect HDR Brightness Tonemapping in Games when
Prefer Color Accuracy set as Color Accuracy Setting
Classification: Plasma
Product: kwin
Version First unspecified
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: colour-management
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
Created attachment 190042
--> https://bugs.kde.org/attachment.cgi?id=190042&action=edit
A video comparing peak brightness differences between settings Prefer Color
Accuracy, and Prefer Efficiency.
SUMMARY
When using Prefer Color Accuracy in HDR settings, tonemapping dims highlights
below calibrated max brightness (either calibrated to 210 nits max SDR
brightness on a 1037 nit screen, or using 21% brightness on the brightness
slider). Not completely sure if this *only* applies to games, or if it affects
other applications as well.
STEPS TO REPRODUCE
1. Set Color Accuracy to "Prefer Color Accuracy."
2. Open an game that supports HDR (my example case is a videogame; specifically
Elden Ring Nightreign for footage of this).
3. Put the application in focus. Observe the brightest parts of the content
that push to the peak brightness of the monitor.
4. Switch the Color Accuracy to "Prefer Efficiency"
5. Repeat step 3.
OBSERVED RESULT
On "Prefer Color Accuracy," the brightest parts of the image that are supposed
to push peak calibrated setting reach nowhere near it, while on "Prefer
Efficiency," the same spots get a lot brighter, matching the set peak.
EXPECTED RESULT
Both settings push the calibrated peak brightness for the monitor
SOFTWARE/OS VERSIONS
Linux: CachyOS
KDE Plasma Version: 6.6.0
KDE Frameworks Version: 6.23.0
Qt Version: 6.10.2
ADDITIONAL INFORMATION
Disabling Tonemapping in /etc/environment fixes the issue by disabling the
tonemapper, but I'm not sure if disabling it will cause more issues down the
line, such as causing other artifacts or oddities in games using HDR.
Attached is my best try at capturing the behavior on video. Watching it, I set
the Color Accuracy setting to Accuracy, then wait for the timeout to reset it
to Efficiency. The phone camera senses the change in brightness and has to
adjust the exposure to account for the extra brightness displayed.
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