Bug 442081 - The algorithm of "Hard Mix (Photoshop)" is different from Photoshop
Summary: The algorithm of "Hard Mix (Photoshop)" is different from Photoshop
Status: ASSIGNED
Alias: None
Product: krita
Classification: Applications
Component: Color models (show other bugs)
Version: 5.0.0-beta1
Platform: Microsoft Windows Microsoft Windows
: NOR normal
Target Milestone: ---
Assignee: Krita Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-09-06 15:12 UTC by thetwo
Modified: 2023-06-23 12:47 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:

Attachments
difference (286.92 KB, image/png)
2021-09-06 15:16 UTC, thetwo 		Details
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Description thetwo 2021-09-06 15:12:51 UTC 
SUMMARY
krita did not further classify and calculate when base color + mixed color = 255.
Post on the KA forum:
https://krita-artists.org/t/about-hard-mix-photoshop/28640


STEPS TO REPRODUCE
1. Paint with red (255 0 0)
2. Create a white layer (255 255 255) and place it below
3. Toggle "Hard Mix (Photoshop)"


OBSERVED RESULT
Red still exists

EXPECTED RESULT
In ps and csp, it is white
Comment 1 thetwo 2021-09-06 15:15:30 UTC 
In photoshop, the mixed results of (127 0 0)-(128 0 0) and (128 0 0)-(127 0 0) are also different. But it is the same in krita.
Comment 2 thetwo 2021-09-06 15:16:30 UTC 
Created attachment 141338 [details]
difference
Comment 3 Halla Rempt 2022-07-05 09:26:50 UTC 
I see from the k-a thread that you already have a fix. Could you make a merge request?
Comment 4 thetwo 2022-07-05 09:50:31 UTC 
(In reply to Halla Rempt from comment #3)
> make a merge request?
Sorry, this is beyond my knowledge…
Comment 5 Bug Janitor Service 2023-06-23 12:47:53 UTC 
A possibly relevant merge request was started @ https://invent.kde.org/graphics/krita/-/merge_requests/1835