Premultiplied alpha handle for driver

Siarhei Siamashka siarhei.siamashka at
Tue Jun 1 09:26:39 PDT 2010

On Tuesday 01 June 2010, Jonathan Morton wrote:
> On Mon, 2010-05-31 at 10:42 +0800, Huang, FrankR wrote:
> > We know the premultiplied alpha will be used sometimes in blend. Is
> > that used in the graphics driver?
> XRender always expects premultiplied alpha in images.  Your previous
> example, with ARGB values of (100,255,0,0) is therefore an invalid pixel
> vector, since the R channel is greater than the A channel.

This is not necessarily invalid. It's more like "additive blending" feature
which is even used by some people:[[Premultiplied%20alpha]]

Best regards,
Siarhei Siamashka

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