https://bugs.kde.org/show_bug.cgi?id=512393
Bug ID: 512393
Summary: Local dimming in HDR mode does not work
Classification: Plasma
Product: kwin
Version First 6.5.3
Reported In:
Platform: Debian unstable
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
The window manager does not activate the monitor’s local dimming when HDR is
enabled. This issue has been present for about six months across KDE versions
from 6.3.6 up to the current one. I also tested Ubuntu 25.10, Fedora
Workstation, Manjaro, and KDE Neon Testing. The problem is identical, although
otherwise system performance when playing movies in MPV and in games through
Proton remained normal. In addition, the brightness adjustment in the HDR
calibration utility under Settings → Display & Monitor somehow affects the
overall brightness of games and movies in HDR mode. When the calibration
wizard’s brightness slider is set to maximum by default, the monitor does
indeed display the image at maximum brightness in both HDR and SDR modes.
However, local dimming does not work — only the overall brightness level
changes. When I boot into Windows 10, the monitor displays HDR movies correctly
without any additional configuration. A few days ago, I tested the Nobara
distribution with KDE 6.5.2. The issue persisted, though the overall image
brightness was slightly higher.
STEPS TO REPRODUCE
1. Enable HDR in KDE system settings window
2. Input on MPV configuration file: vo=gpu-next
gpu-api=vulkan
profile=high-quality
hwdec=yes
gpu-context=auto
target-peak=1000
hdr-compute-peak=yes
hdr-contrast-recovery=0.30
hdr-peak-percentile=99.995
dither-depth=10
temporal-dither=yes
dither=ordered
If “gpu-next” is selected in the **vo** option, the video appears washed out.
However, if I load this configuration file in Celluloid, the colors in the
video look normal. But in both players, as well as in games, the monitor’s
local dimming does not work.
3. Launch MPV or game under steam with proton-ge. Proton settings on all games:
PROTON_ENABLE_AGS=1 PROTON_ENABLE_WAYLAND=1 PROTON_ENABLE_HDR=1 %command%
OBSERVED RESULT
Video looks some washed out and local dimming does not work.
EXPECTED RESULT
Video with normal colors and local dimming.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian Sid and KDE 6.5.3
KDE Plasma Version: 6.5.3
KDE Frameworks Version: 6.20.0
Qt Version: 6.9.2
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