Do I must divide alpha out if DST is non-premultiplied?

In some of the blending equations, alpha is divided out if the source is premultiplied and the destination is non-premultiplied. Do I must do the division? Are there any applications which will use premutiplied source and non-premultiplied destination? I’m just thinking it is very expensive to do a division per pixel. Anyone could help me? Thanks a lot!

I just disallow non-premultiplied egl-surfaces for rendering with OpenVG :slight_smile:

That way I can do all my rendering in premultiplied colorspace and never run into the problem to do a post-divide step for rendering. Makes things MUCH easier to deal with.

For format conversion between VGImage objects you need to do a postdivide here and there. But those operations usualy don’t happen that often.

Btw, if you think the divide per pixel is slow - wait until you’ve seen the equation for radial gradients… A per pixel square root is lurking there.

Hope that helps,

Well, sounds good to me! :slight_smile:
Hope not many people using the radial gradients, although I like those images…