Bug 501944 - Low fractional scale factors are still affected by significant blurriness
Summary: Low fractional scale factors are still affected by significant blurriness
Status: CONFIRMED
Alias: None
Product: kwin
Classification: Plasma
Component: general (show other bugs)
Version: 6.3.3
Platform: Manjaro Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
: 502099 (view as bug list)
Depends on:
Blocks:
 
Reported: 2025-03-24 16:11 UTC by alt
Modified: 2025-04-06 16:26 UTC (History)
4 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
keyboard icon at 105% scale (101.49 KB, image/png)
2025-03-24 16:11 UTC, alt
Details
Keyboard icon at 100% scale (94.06 KB, image/png)
2025-03-24 16:13 UTC, alt
Details
Keyboard icon at 125% scale (118.22 KB, image/png)
2025-03-24 16:14 UTC, alt
Details
Brave icon at 110% scale (136.07 KB, image/png)
2025-03-24 16:15 UTC, alt
Details
Brave icon at 100% scale (103.73 KB, image/png)
2025-03-24 16:16 UTC, alt
Details
Image comparing icons at different scales (3.83 MB, image/jpeg)
2025-03-28 20:59 UTC, alt
Details

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Description alt 2025-03-24 16:11:52 UTC
Created attachment 179693 [details]
keyboard icon at 105% scale

SUMMARY
Some fractional scale factors (like 105%, 110%, 115%, 120%) are still affected by significant blurriness.

STEPS TO REPRODUCE
1. Go to Display and Monitor settings and change the scale factor to 105%.
2. Use the zoom function (Meta++) to see the difference in icons' pixels.

OBSERVED RESULT
The icons are too blurry compared to 100% or 125% scales.

EXPECTED RESULT
Less blurriness.

SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux 
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2
Kernel Version: 6.12.19-1-MANJARO (64-bit)
Graphics Platform: Wayland
Comment 1 alt 2025-03-24 16:13:42 UTC
Created attachment 179694 [details]
Keyboard icon at 100% scale
Comment 2 alt 2025-03-24 16:14:49 UTC
Created attachment 179695 [details]
Keyboard icon at 125% scale
Comment 3 alt 2025-03-24 16:15:48 UTC
Created attachment 179696 [details]
Brave icon at 110% scale
Comment 4 alt 2025-03-24 16:16:19 UTC
Created attachment 179697 [details]
Brave icon at 100% scale
Comment 5 alt 2025-03-24 16:28:47 UTC
As you can see from the attached images, the pixels become too faded and whitish for fractional scales, while I think that they should retain a less faded color, closer to the 100% scale.
Comment 6 alt 2025-03-24 16:37:20 UTC
The only exception are scales like 125%, 150% and 175%. These are OK. 
You see the difference between the 105% and the 125% images. The darker pixels in 125% scaled icon are very similar in color to the dark background. The same should happen in some way for the 105% scaled icon but it doesn't.
Comment 7 Nate Graham 2025-03-25 23:09:02 UTC
Is the issue only seen in panel/tray icons?

How about other UI elements in Plasma, or even in apps? Can you test in a bunch of different places on your system?
Comment 8 alt 2025-03-28 20:39:47 UTC
Potentially everything that scales could be affected by this issue, probably even text in some edge cases, but it is seems OK to me.
Not only the icons in the tray but also icons in desktop files and menus are affected, apps included. Some icons in some apps and are not affected, though.
I tested in LyX, Gimp, Krita, Dolphin, the system settings and the launcher menu. Barring Krita, in all this apps  I noticed that some icons become blurred after scaling.
Comment 9 alt 2025-03-28 20:59:32 UTC
Created attachment 179827 [details]
Image comparing icons at different scales

As you can see from the image, the keyboard icon in the System Settings app becomes blurred, in particular the green pixels on the upper right are almost completely faded out, while they should remain visible like in the 125% scale (although this is still not perfect).
From the nvtop desktop icon it can be seen that the color is not consistent across different scales, sometimes it's darker for some letters, sometimes lighter (for instance, the T at 110% is lighter in color than the T at 120%).
Comment 10 Nate Graham 2025-04-06 16:22:50 UTC
It looks like the blurriness increases the closer we get to 100%, without actually being 100%.

To a certain extent this makes sense since 100% will be pixel-perfect, while anything larger but below 200% will not be pixel perfect. It appears that the lack of pixel-perfection becomes is more easily hide-able the higher the scale is.

I wonder how fixable this really is. KWin may have to get extremely clever with its scaling algorithms for low fractional scales.
Comment 11 Nate Graham 2025-04-06 16:23:00 UTC
*** Bug 502099 has been marked as a duplicate of this bug. ***