Bug 482978

Summary: Colorblindness Correction effect causes blurs on a 1.25x/1.75x scaled screen
Product: [Plasma] kwin Reporter: bene.danika
Component: effects-variousAssignee: KWin default assignee <kwin-bugs-null>
Status: CONFIRMED ---    
Severity: normal CC: mobile.harvey, nate, stefanspr94
Priority: NOR Keywords: qt6
Version: 6.0.1   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed In:
Attachments: Colorblindness Correction off (sharp) vs on (blurry).

Description bene.danika 2024-03-09 13:18:58 UTC
Created attachment 166791 [details]
Colorblindness Correction off (sharp) vs on (blurry).

SUMMARY
When using fractional scales 1.25, 1.75 or anything else not divisible by 0.5 (1.0 and 2.0 work, 1.5 also interestingly works), and having the Colorblindness Correction desktop effect enabled, floating windows become blurry.


STEPS TO REPRODUCE
1. Display & Monitor -> Scale: 125% or 175%.
2. Desktop Effects -> enable Colorblindness Correction.

OBSERVED RESULT
Floating windows become visibly washed out on-screen.

EXPECTED RESULT
Floating windows remain as sharp as they are with the effect disabled.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
(available in About System)
KDE Plasma Version: 6.0.1
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2

ADDITIONAL INFORMATION
Fullscreen windows and panels(?) are interestingly unaffected by this.
Comment 1 Nick 2024-03-16 08:45:57 UTC
Hi - thanks for reporting this. I can also duplicate this on my stock Neon installation but the effect is slightly less obvious than in your screenshot. However I do also see things get a little bit blurry at any scaling setting (i.e. 100%, 125%, and 150%). 

I'm no expert in how the colorblindness is implemented but since it is possible the blurriness might negate the benefits of enabling the colorblindness setting I'll mark this as CONFIRMED and hope a dev can take a look and comment at a more technical level.

Thanks
Nick
Comment 2 Stefan Springer 2024-06-01 17:18:53 UTC
Possibly related: https://bugs.kde.org/show_bug.cgi?id=483224

Please fix! This breaks customization for every Plasma 6 user with fractional scaling, especially since being able to scale via specifying font DPI as a workaround isn't available anymore.