hi instinct,
for this time its a broadcast thing, i can fix it simple by rendering before white, but isn’t it possible to get a clean alpha?
I’ve try’d even the cubic, its all the same problem there.
How are you lighting this scene? Is the background white (255,255,255) or something above (HDRI?) You’ve probably seen the problems with jaggies on overexposed items-maybe it’s related to this?
the objects are premultiplied on the black background so the black is mixed in the semi transparent pixels at the edges, solutions are to save whithout a premultiplied alpha or in PS go to layer/matting/remove black matte
There must be a “premultiplied alpha” option that you need to (un)check somewhere… either when saving the image, or when loading it in another program. TGA’s have such an option, not sure about PNG files.
This is expected in the RGB channel with non-premultiplied alpha, yes. The idea is that the RGB channel combined with the alpha will give you the nice edges. In that case, the RGB channel itself will look jaggy, but the alpha will smooth this out later on in your compositing application. The whole problem originally appeared because the RGB channel was smooth - once you smooth that again with the alpha, you get the black edges.