[Bf-codereview] Alpha premul pipeline cleanup (issue 7018048)

[sergey.vfx at gmail.com]

On 2012/12/29 22:41:44, xavier.thomas.1980_gmail.com wrote:
> > However, byte buffers behaves quite fuzzy. When i do a stroke with
white
> > brush on complete transparent image, i should see the whole stroke
being
> > white in RGB display mode, but it fades up to darkish colors to the
> > sides of brush. Converting pixels from straight-byte to premul-float
in
> > IMB_rectblend and using IMB_blend_color_float doesn't give correct
> > result here.


> Darkish colors in the semitransparent areas is often a sign of having
> premultiplied colors by alpha twice or more.

I know this and it doesn't seem to be this case. If you'll try the patch
you'll notice that blending is much more "steppy" than just multiplying
alpha twice. It could be extra premul, but there seems to be some other
issue involved here.

https://codereview.appspot.com/7018048/