>It depends on what you are doing weather pre multiplied alpha is useful >or not. For compositing and image warping pre multiplied alpha is great. for >color correction pre-multiplied alpha just gets in the way. Since >pre-multiplying the alpha does throw away a few bits of information my >preference is for non-pre-multiplied alpha. I know 3D software that outputs pre or non-pre, user selectable, but read only pre. The manual says all that, and recommends non-pre for "drawing programs". What I do not understand, is why I would like pre for compositing? If I have an image with pre, when I composite with another image, I will get damaged borders, instead of true composition based in the alpha, no? If software knows it, it can be fixed... but after lossing precission, no? GSR
