Bug 510947

Summary: Transparent background blur color reproduction is wildly off
Product: [Applications] konsole Reporter: Oded Arbel <oded>
Component: generalAssignee: Konsole Bugs <konsole-bugs-null>
Status: REPORTED ---    
Severity: normal    
Priority: NOR    
Version First Reported In: 25.08.2   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: screenshot showing the effect with 30% transparency, compared to the actual wallpaper that was used (image was scaled down)
screenshot showing the effect, compared to the actual wallpaper that was used (image was scaled down)

Description Oded Arbel 2025-10-23 09:01:07 UTC
Created attachment 186035 [details]
screenshot showing the effect with 30% transparency, compared to the actual wallpaper that was used (image was scaled down)

SUMMARY
When using "transparent background" in the Konsole appearance, with "blur background" enabled, the effect massively mutes almost all colors but over saturates red and similar colors. See attachments.

I've noticed this effect after the update to 6.5 - so I think this is the likely cause as this effect is really jarring, so much that I had to turn off blur to continue working, that I think it is new to Plasma 6.5

STEPS TO REPRODUCE
1.  In Konsole, click Settings -> Edit current profile -> Appearance -> Edit
2. Check "Blur background", and set "Background transparency to 100%"
3. Click Apply

OBSERVED RESULT
Any red in the background is brightened while any non-red is muted (the background usually just the wallpaper, but this also affects whatever window is behind Konsole).

EXPECTED RESULT
There shouldn't be massive change in colors just from blurring.

SOFTWARE/OS VERSIONS
Operating System: KDE neon User Edition
KDE Plasma Version: 6.5.0
KDE Frameworks Version: 6.19.0
Qt Version: 6.9.2
Kernel Version: 6.14.8-061408-generic (64-bit)
Graphics Platform: Wayland
Processors: 20 × 12th Gen Intel® Core™ i7-12700H
Memory: 32 GiB of RAM (31.0 GiB usable)
Graphics Processor: Intel® Iris® Xe Graphics

ADDITIONAL INFORMATION
A. See attached screenshots
B. I ran the color picker on the konsole rendering, with blur on and off, and here are some numbers:

Redish area: unblurred HSV (RGB) = 6, 241, 236 (236, 38, 13) ; blurred HSV (RGB) = 13, 215, 255 (255, 87, 40)
Light gray area: unblurred HSV (RGB) = 26, 25, 181 (181, 171, 163); blurred HSV (RGB) = 20, 51, 175 (175, 152, 140)

We can see that there's a slight shift towards red, in general, but also that reds are brightened by quite a lot (~7%, but its clamped so it could be more) while gray areas are actually darkened a bit (-3% in this example, which from testing multiple gray light levels - appears representative).

This effect is very jarring.
Comment 1 Oded Arbel 2025-10-23 09:10:58 UTC
Created attachment 186036 [details]
screenshot showing the effect, compared to the actual wallpaper that was used (image was scaled down)

retook screenshot with 100% transparency (that is not what I normally use) but the effect is more pronounced that way.