Bug 500118 - Night light got subjectively worse
Summary: Night light got subjectively worse
Status: RESOLVED INTENTIONAL
Alias: None
Product: kwin
Classification: Plasma
Component: night color (show other bugs)
Version: master
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-02-15 10:07 UTC by daron439
Modified: 2025-02-22 11:00 UTC (History)
2 users (show)

See Also:
Latest Commit:
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Sentry Crash Report:


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Description daron439 2025-02-15 10:07:30 UTC
SUMMARY
After updating from e56d3de to 4205a9b I noticed that the effect is less strong (more blue light). I tried lowering the temperature and my colors got weird: at 2500K grey turns into light green, the breeze dark background in dolphin gets much much darker. I have no scaling. Results are the same with both Color Profiles "built-in" and "None".

This is caused by https://invent.kde.org/plasma/kwin/-/commit/4205a9b9423d08678483b5c6fa7da2dc5ed29628
I don't see this on https://invent.kde.org/plasma/kwin/-/commit/c523fce6c1792969fca36575a2ace43c75f69b8a

STEPS TO REPRODUCE
1. Enable Night Light
2. Play with the slider

OBSERVED RESULT
Darker colors change significantly

EXPECTED RESULT
There are no significant changes

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: 
KDE Plasma Version: 6.3.80
KDE Frameworks Version: 6.12.0
Qt Version: 6.9.0

ADDITIONAL INFORMATION
NVIDIA 570.86.16
Comment 1 Zamundaaa 2025-02-17 16:31:44 UTC
Yes, this is intentional. It was incorrect without a color profile before - now it's the same strength as in Plasma 6.2

At very low color temperatures, colors do become weird, simply because most displays straight up can't show these colors. 2000K is a color that normal sRGB displays can present, so colors get distorted as you get close to it.
Comment 2 Paul Meier 2025-02-17 23:10:25 UTC
(In reply to Zamundaaa from comment #1)
> Yes, this is intentional. It was incorrect without a color profile before -
> now it's the same strength as in Plasma 6.2
> 
> At very low color temperatures, colors do become weird, simply because most
> displays straight up can't show these colors. 2000K is a color that normal
> sRGB displays can present, so colors get distorted as you get close to it.

So what now? Night light is pretty much unusable at this time because colours change significantly even at lower night light values.
Not just that, it is visible on screenshots, which means I have to disable night light if I want to screenshot anything.
Night light had no effect on colours in previous plasma version. Or of it did, it wasn't noticeable.
I tested at 3000K and the difference in colour was clear to see.