Patch for smudge

Boudewijn Rempt boud at
Thu Sep 23 10:49:07 CEST 2010

On Thursday 23 September 2010, at wrote:
> This is weird problem. We have similar darkening in the deform brush.
> The black smudge does not appear in rgb 16-bit scRgb linear. Maybe some gamma 
> correction has to be added for rgb8? 
> Don't we have some bug in rgb8 colorspace then?

No, this is not really a bug, it's an artefact of a non-linear colorspace. It might be possible to compensate for it, by converting the paint devices to 16 bit linear rgb before doing the smudge and then back, or by doing some gamma adjustment (i think ImageMagick does that these days).

> Question is if we do not want to throw away the size change for smudge.

We could make it optional, but I think it's not something to disable altogether.

> > I also spotted a silly BUG related to SELECTING composite ops:
> > --Pick the smudge op.
> > --Pick the copy composite op.
> > --Then switch to the pixel brush using the hotkey approach (right
> > click or middle click of the mouse?).
> > --You'll see that the copy composite op is selected in practice (paint
> > with it), you'll also see that the name of the composite op doesn't
> > appear on the list (it shouldn't be selectable in the first place!).
> To please. Could you look at this boud? Or if busy, put it 
> on my Action Plan III.

If Pentalis adds it bko, I can look into it.

> I don't see any idea for solution here. Fix the bugs! does not help me. 
> The problem is complicated. There is no such a thing like specification for 
> smudge so it is hard to solve it. I studied GIMP code a little, but I was not 
> able to understand it. 

This is somewhat helpful: It also mentions that we need a really small spacing for smudge to be non-blocky. Unfortunately a search for "smudge tool code" mostly returns complaints from Adobe users that the smudge tool in Photoshop is broken...

Boudewijn Rempt |
Ceterum censeo lapsum particulorum probae delendum esse

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