Hello. I am trying to force 10 bit color on my main monitor (alienware aw3423dw). I tried to set the KWIN_DRM_PREFER_COLOR_DEPTH=30 but i have no way to confirm if it is working or not. How can i verify that setting worked? I am using a nvidia gpu with the latest open kernel drivers.
I assume that you will need to enable HDR in the display settings.
You can see info on HDR with the command kscreen-doctor -o which.
Look for the HDR: setting in the output.
I don’t have this selector of bits per color because I am using a DP in both sides. So, I only have the 10 bit supported by my monitor (if was HDMI, will be 8/10 and maybe 12).
My monitor is LG 27LS75Q-B.
Regards
same issue here…
strangely, 10-bit was working fine in x11, but no hdr. now in wayland, hdr is working fine but i can’t seem to
enable 10-bit
Doesn’t HDR mean you have 10bit/colour or better?
Quite new on linux so cant tell on linux but i know for a fact on windows it is a no. there was 10 bit monitors way way before HDR was a thing too.
Try switching to “Prefer accuracy” for color.
i believe that may be true, but i just wish i could somehow confirm it’s actually 10-bit.
also, my monitor info in the OSD menu is only showing 8bps color depth
Nothing seems to have change in the UI
for some reason when i try that, my pc locks up & won’t boot back into the desktop. i have to delete or edit the ~/.config/kwinoutput.json file back to “PreferEfficiency”. maybe my monitor just can’t do both at the same time 
There’s no way to know really, the driver APIs for that is unfortunately still entirely missing KWin always uses 10bpc though on all GPUs that support it
About the selector for limiting bpc, are you on NVidia? The proprietary driver doesn’t support the setting yet.
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Im on nvidia ye. not sure how other operating systems does it. would think there is some way to do it. someone mentioned drm_info but that is like super duper verbose. There is this tool that you can use in combination with reshade that shows the true HDR color output of the screen live.EndlesslyFlowering’s ReShade_HDR_shader, but that still leaves the question on how to truly limit it to 10bit
Other operating systems simply have APIs for it… we don’t yet.
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Ah that makes sense. Is the API that KDE is missing from AMD, Intel and Nvidia?
Yes, the kernel would need to add the API and the drivers would need to support it
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Wait how did you manage to get 10 Bit in that box? Thought it was not possible. What Linux version are you running. What version of kde and are you running on x11 or wayland?
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wrong reply. sorry i ment to reply to @throttlemeister
just wanted to follow up here as i just discovered i could enable HDR & 10-bit color simultaneously by lowering the refresh rate in the Display Configuration… seems to be some sort of bandwidth limitation with my setup