Bug 416699

Summary:	Contrast Effect gives wrong colors on saturation
Product:	[Plasma] kwin	Reporter:	veggero <niccolo.venerandi>
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	REPORTED ---
Severity:	minor	CC:	kde, nate
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description veggero 2020-01-24 16:18:38 UTC

SUMMARY

The contrast effect saturates in such a way that the result color does not look good on the wallpaper anymore; Here's a clear example of what I expect, and what the contrast effect do:

This is my wallpaper: 
https://i.postimg.cc/PxMDS6Ld/Volna4k-Edit.png

This is my manually saturated wallpaper: 
https://i.postimg.cc/QdsHyg3t/image-4.png

This is a dialog (without contrast effect) applied on top of the above image: 
https://i.postimg.cc/MpKzB9wy/Screenshot-20200124-171123.png

Proper orange!

Here's a dialog using the contrast effect and the saturation value (strengthen to make my point more clear):
https://i.postimg.cc/qMD5mwnc/image.png

Bad yellow-ish color; I'm not sure how this was computed. It is also based on the "BackgroundNormal=" color in the color file, as dark themes use a more proper saturated color. 

STEPS TO REPRODUCE
1. Change contrast of Breeze theme from 0.2 to 1.0
2. Change saturation to 1.7
Expected: proper orange
Observed: bad yellow-ish tint

SOFTWARE/OS VERSIONS
KDE Plasma Version: 5.17.5
KDE Frameworks Version: 5.6
Qt Version: 5.14

Comment 1 veggero 2020-01-24 16:44:14 UTC

Setting intensity=1 makes the contrast-effected dialog look like the one did by manually changing the saturation. Is it possible that it's calculated wrong maybe?