Bug 501748 - MyPaint Engine brushes too bright in 16bit integer/channel color depth
Summary: MyPaint Engine brushes too bright in 16bit integer/channel color depth
Status: REPORTED
Alias: None
Product: krita
Classification: Applications
Component: Brush engines (other bugs)
Version First Reported In: 5.2.9
Platform: Microsoft Windows Microsoft Windows
: NOR normal
Target Milestone: ---
Assignee: Krita Bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-03-19 15:20 UTC by sirmcscotalot
Modified: 2025-04-09 18:03 UTC (History)
1 user (show)

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


Attachments
Shows brush strokes at 8 bit and 16 bit, with Krita brush engine and MyPaint brush engine respectively (126.96 KB, image/png)
2025-03-19 15:20 UTC, sirmcscotalot
Details
Additional image demonstrating it is not a transparency issue (75.12 KB, image/png)
2025-04-09 17:54 UTC, sirmcscotalot
Details

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Description sirmcscotalot 2025-03-19 15:20:13 UTC
Created attachment 179577 [details]
Shows brush strokes at 8 bit and 16 bit, with Krita brush engine and MyPaint brush engine respectively

SUMMARY
When using any myPaint engine brush, any color applied comes out brighter than what was picked if using 16 bit integer/channel color depth. Tested with included myPaint brushes such as "Wet Paint Plus"

STEPS TO REPRODUCE
1. Set image to RGB/Alpha, 16 bit integer/channel mode, default profile
2. Pick myPaint engine brush and any color
3. Paint at max opacity

OBSERVED RESULT
The applied color will come out brighter than what was picked, regardless of pen pressure

EXPECTED RESULT
The picked color should be applied when using max pressure

SOFTWARE/OS VERSIONS
OS
  Windows 11

Krita
 Version: 5.2.9 (git ac6cae8)
 Installation type: installer / portable package
 Hidpi: true

Qt
  Version (compiled): 5.15.7
  Version (loaded): 5.15.7

OS Information
  Build ABI: x86_64-little_endian-llp64
  Build CPU: x86_64
  CPU: x86_64
  Kernel Type: winnt
  Kernel Version: 10.0.22631
  Pretty Productname: Windows 10 Version 2009
  Product Type: windows
  Product Version: 10
Comment 1 Wolfgang Baer 2025-04-08 20:00:55 UTC
I tested on Windows 10, Krita 5.2.9
Quick brush engine b) Basic-1 brush
MyPaint engine Wet Paint Plus brush

Both brushes create the same colors in 16bit (I tried with gamma 1.0 icc profile and gamma sRGB icc profile).

Note: The Wet Paint Plus has smudge settings active - you might need to make multiple strokes on top of each other to get to full saturated colors.
Comment 2 sirmcscotalot 2025-04-09 17:54:28 UTC
Created attachment 180128 [details]
Additional image demonstrating it is not a transparency issue
Comment 3 sirmcscotalot 2025-04-09 18:03:43 UTC
(In reply to Wolfgang Baer from comment #1)
> I tested on Windows 10, Krita 5.2.9
> Quick brush engine b) Basic-1 brush
> MyPaint engine Wet Paint Plus brush
> 
> Both brushes create the same colors in 16bit (I tried with gamma 1.0 icc
> profile and gamma sRGB icc profile).
> 
> Note: The Wet Paint Plus has smudge settings active - you might need to make
> multiple strokes on top of each other to get to full saturated colors.

Thank you for your input~ 
Interesting to see that our experience is not the same. I have supplemented another screenshot demonstrating that it is not a saturation/opacity issue (I also used my mouse to rule out a pressure sensitivity issue with my art display). I also retested with both sRGB-elle-V2-srgbtrc and sRGB-elle-V2-g10 and got the same results as before.