Bug 383066

Summary: Improvement suggestion on the deform brush engine
Product: [Applications] krita Reporter: reptillia39
Component: Brush enginesAssignee: Krita Bugs <krita-bugs-null>
Status: RESOLVED WORKSFORME    
Severity: normal CC: griffinvalley, halla
Priority: NOR    
Version First Reported In: 3.2.0-beta.2   
Target Milestone: ---   
Platform: Other   
OS: Microsoft Windows   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description reptillia39 2017-08-03 04:46:14 UTC 
The current deform brush engine sometimes seem to add into low value/brightness/luminosity when using the deform move tool. For some artist, this is a inconvenience for artists who wants to avoid adding darkness when deforming by using the opacity. 

For example - Results when lowering opacity - http://i.imgur.com/CwQwn0P.png

You get a nice, and interesting liquify effect. 

Now, let me try with a test area - http://i.imgur.com/hTX7WBD.png . The area I am going to to deform is on the center of the screen, at full opacity, I get something like this - http://i.imgur.com/YpseI4A.png . Note that there's no sign of light area as it been erased. Now, with lowered brush opacity - http://i.imgur.com/MN0Wj4g.png . See how much nicer it looks?

What I'm trying to say is that the deform brush tool should somehow be able to retain lightness as much as it can. It would also make artists' workflow so much faster as they don't have to deform brush so many time to get an effect.

I hope I explained it well.

Extra Information: Krita 4.0 Pre-Alpha, and 3.2 Beta Tested on Windows 10x64
Comment 1 wolthera 2017-08-03 21:54:38 UTC 
Does turning off "bilinear filtering" make a difference in this effect?
Comment 2 reptillia39 2017-08-04 16:27:04 UTC 
The results looks extremely pixelated (meaning useful for pixel art which requires deformation, but not for anything else), but luminosity is better preserved with that option turned off.
Comment 3 reptillia39 2017-08-04 18:16:01 UTC 
Ok, I found out how to keep the luminosity preserved with setting blending mode to lighten. It seems that the brush works only with few blending modes. Same to the color smudge.
Comment 4 Halla Rempt 2017-11-23 09:18:44 UTC 
That's a matter of mathematics, I'm afraid.