https://bugs.kde.org/show_bug.cgi?id=525436
Bug ID: 525436
Summary: Raising peak brightness with hdrcalibrator raises
blacks
Classification: Plasma
Product: KScreen
Version First 6.7.4
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: common
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
DESCRIPTION
I have a QD-OLED monitor (the MSI 272QP x50) that has three different HDR
modes: TrueBlack 500, Peak 1000 nits, and EOTF Boost. TrueBlack 500 mode has a
peak brightness of ~530 nits, but Peak 1000 and EOTF boost raise the peak
brightness to ~1000 nits. If I change to either Peak 1000 nits or EOTF boost
mode, enter the hdr calibration wizard, and raise peak brightness to 1000 nits,
all parts of the screen that should be 0 nits and turn off completely become a
very dark gray. It's well documented that QD-OLEDs in the "peak" or "boost"
modes have raised blacks, but 0 nits should still be 0 nits. I also still think
there's something going wrong on KDE's end, because if I lower the peak
brightness back down to 530 nits while still in Peak 1000 nits or EOTF boost
mode, the blacks become black again. I can also make blacks appear black by
setting minBrightnessOverride to a value below 0.0038 nits, but the hdr
calibration wizard shouldn't change the minimum brightness at all. Plausibly
this behavior affects WOLEDs as well, but I can't test that. Very similar to
this bug, but I think being affected by the peak brightness setting
differentiates it: https://bugs.kde.org/show_bug.cgi?id=494128
STEPS TO REPRODUCE
1. Enter EOTF Boost or Peak 1000 nits mode
2. Raise maxPeakBrightnessOverride to 1000 nits with the hdr calibration wizard
3. Blacks that should be off completely are very dark gray
OBSERVED RESULT
Changing the peak brightness with the hdr calibration wizard changes the black
floor even if I don't change minBrightnessOverride.
EXPECTED RESULT
Changing the peak brightness should have no effect on the black floor.
SOFTWARE/OS VERSIONS
Operating System: CachyOS Linux
KDE Plasma Version: 6.7.4
KDE Frameworks Version: 6.29.0
Qt Version: 6.11.2
ADDITIONAL INFORMATION
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