Bug 430372 - HSV Filter degrades quality of CMYK images
Summary: HSV Filter degrades quality of CMYK images
Status: CONFIRMED
Alias: None
Product: krita
Classification: Applications
Component: Filters (show other bugs)
Version: git master (please specify the git hash!)
Platform: Other Other
: NOR normal
Target Milestone: ---
Assignee: Krita Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2020-12-14 11:50 UTC by Dmitry Kazakov
Modified: 2024-08-22 16:38 UTC (History)
1 user (show)

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Description Dmitry Kazakov 2020-12-14 11:50:19 UTC 
SUMMARY

When opening HSV filter on an CMYK image the quality of the image degrades right after opening the filter, without changing any controls.

STEPS TO REPRODUCE
1. Create/open any colorful image in CMYK space.
2. Open HSV filter
3. The image starts looking desaturated, even though you didn't change any controls

The problem is because HSV filter converts the image into RGB before processing. I guess we should somehow use CMYK-complements instead of RGB conversion to make this filter work correctly. CMYK-complements are defined in PDF specification for blending modes, so that it should work fine with the filters as well.

This bug is very related, but different:
https://bugs.kde.org/show_bug.cgi?id=424525
Comment 1 wolthera 2021-09-08 08:56:05 UTC 
I guess I'll confirm this, but we're going to need more research linked to this...
Comment 2 Dmitry Kazakov 2024-08-22 16:38:36 UTC 
Remove triaged keyword from CONFIRMED bugs