https://bugs.kde.org/show_bug.cgi?id=414386
Dmitry Kazakov <dimul...@gmail.com> changed:
What |Removed |Added
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CC| |dimul...@gmail.com
--- Comment #3 from Dmitry Kazakov <dimul...@gmail.com> ---
Hi, acc4commisions!
That is a very interesting report :) I've never though about these effects.
Most of them are the consequence of the design decisions we did for
optimization purposes. So before explaining them I would like to ask you, what
is your workflow? Why do you want these edges to be smooth?
Detailed explanation:
> 'Normal' produces blocky edges.
By definition, when alpha is null, the value of color channels is undefined (in
normal user workflow). Therefore, if we know that the destination alpha is
null, we just copy the color of source channels, disregarding alpha. It is
faster, and normal users will not see the difference.
And you see blocky edges, because in "Normal" composite op we don't operate on
individual pixels, but on strides of 8(!) pixels (due to AVX CPU
optimizations). If you go to Settings->Performance->Disable AVX Optimizations
and restart Krita you'll see that the edges become less blocky, like in
"Overlay", but without artifacts.
> 'Overlay', ... etc produces sharp edges with artifacts
It happens because of a division in 8-bit numerical space. When alpha is low,
then division/multiplication operations become non-stable. If you switch to
32-bit float color space, then the bug will disappear. Theoretically, we can
try to fix it: Normal doesn't have this effect, though it has a little bit
different blending. Though it might take quite a bit of time with uncertain
results.
> Only 'Luminosity / Shine (SAI)' produces the smooth result
It is actually a bug in 'Luminosity / Shine (SAI)' and it should be fixed with
410516 :) This blending mode blends-in black color into the edges, which makes
the edge look smooth. Just compare the strokes on white background.
> Plus, there's this weird black triangles appears in vector text areas...
Yes, it is a bug and should be fixed. It would be better if you added a
separate ticket for that.
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