The current HDR calibration tool is pretty lackluster ~ yes, you can set you peak HDR brightness, but there is no means of really figuring out to set SDR brightness such that it won't clip. So I ask if it could be improved to be able to let us properly figure out the right SDR brightness for our individual monitors. Something like how many games ask to you to calibrate until you can no longer see a difference in Windows HDR Calibration app is an excellent reference point ~ that is, on how to let us setup HDR properly: this video, timestamp included, https://youtu.be/xoo7sSpCn1Y?t=136 gives a great overview of what I'm asking for, I guess.
I didn't include a page for FALL because that value is more often than not completely ignored, and it does require blasting the user with a white fullscreen window... but giving a hint for what the max reference luminance should be sounds like a good enough reason to do it anyways.
*** Bug 507440 has been marked as a duplicate of this bug. ***
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kscreen/-/merge_requests/429
Git commit f5a4548ba3d4fabb73e8063dfb7e9724e45b86be by Xaver Hugl. Committed on 04/11/2025 at 17:10. Pushed by zamundaaa into branch 'master'. hdrcalibrator: add a page for the maximum fullscreen average luminance This value is usually ignored by applications (and by KWin's own tonemapping too), but it can offer a good hint for what the maximum SDR luminance should be. M +16 -0 hdrcalibrator/hdrcalibrator.cpp M +8 -0 hdrcalibrator/hdrcalibrator.h M +103 -3 hdrcalibrator/ui/Main.qml https://invent.kde.org/plasma/kscreen/-/commit/f5a4548ba3d4fabb73e8063dfb7e9724e45b86be
*** Bug 514982 has been marked as a duplicate of this bug. ***
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kscreen/-/merge_requests/464
Git commit 07bdaca58af22adacc5111c6c9f96b6378af1321 by Xaver Hugl. Committed on 23/02/2026 at 13:00. Pushed by zamundaaa into branch 'master'. hdrcalibrator: remove fullscreen average calibration page again Unfortunately on most common HDR displays, it doesn't work as expected, and just results in the peak luminance. This confused a lot of users, which was the opposite of its intended purpose. If available, the max average luminance reported in the EDID is instead used to recommend a sensible max reference luminance value to the user. M +8 -138 hdrcalibrator/ui/Main.qml https://invent.kde.org/plasma/kscreen/-/commit/07bdaca58af22adacc5111c6c9f96b6378af1321
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kscreen/-/merge_requests/466
Git commit 525884029664c7a93587fcc11972c844cd2c66ff by Xaver Hugl. Committed on 23/02/2026 at 13:42. Pushed by zamundaaa into branch 'Plasma/6.6'. hdrcalibrator: remove fullscreen average calibration page again Unfortunately on most common HDR displays, it doesn't work as expected, and just results in the peak luminance. This confused a lot of users, which was the opposite of its intended purpose. If available, the max average luminance reported in the EDID is instead used to recommend a sensible max reference luminance value to the user. (cherry picked from commit 07bdaca58af22adacc5111c6c9f96b6378af1321) Co-authored-by: Xaver Hugl <xaver.hugl@kde.org> M +8 -138 hdrcalibrator/ui/Main.qml https://invent.kde.org/plasma/kscreen/-/commit/525884029664c7a93587fcc11972c844cd2c66ff
I'm sure this is a known issue but my display like many other HDaRen't screens reports values such as: Desired content max luminance: 97 (408.759 cd/m^2) Desired content max frame-average luminance: 97 (408.759 cd/m^2) When in reality the KDE's calibration tool indicates 388 (or 389 for truly ghostly wisp of a test pattern) as the average and 394 as the peak luminance. I don't know where the frame average luminance is used but clearly 408 is not the correct value, if the KDE's calibration tool is to be trusted here. The only confusing thing for me is that WIndows app calibration checkbox - I read the discussion regarding it but I still have no idea, if the correct thing would to keep it checked or not. Or why it's even a thing, since, I guess, it should just be kept enabled?
Those values seem close enough to not be an issue. > Windows app calibration checkbox - I read the discussion regarding it but I still have no idea, if the correct thing would to keep it checked or not. Or why it's even a thing, since, I guess, it should just be kept enabled? It's a thing because you may have multiple HDR screens, but we can only make Windows apps work as expected on one of them.
Okay, I just assumed it was significant, since when the max, average and SDR brightness patches were shown at the end of calibration, I could tell the difference between 394 and 388. I still think my point stands that the message is utterly confusing and has no guidance on which value is better for particular use cases, since, if I do ever get a second screen and keep this around as a vertical reading panel or something, would it have been better if that box had been checked or not? Or will I need to readjust all my games irrespective of that checkbox state?