Render output colour dept, Premult. Alpha

Hi all,

Not a pro-user, just started with AE 4 months ago, so my apologies if I’m asking obvious questions.

- Does anyone know what colour dept is used for render output? I understand this differs from codec, but ProRes can contain various colour dept I believe?

- Furthermore, what colour is used for ‘premultiplied alpha’, just black? And is this black based on my screen ( adjusted e.g. / profile) ? The thing is, is that my rendered clips show a white background in preview mode in finder? Have to tweak matte in AE allot, or remove colour matting and use track mattes. File interpretation is set correctly, leave ‘preserve RGB unchecked’ working in 32 bit.

Thanks a bunch,

Gr Joep

Ok found the other post on colour profile output ( rec 709), so that part is clear.


When you choose Premultiplied alpha in the export options PI multiplies with pure black i.e. RGB=0,0,0. When I last tested in AE in early June there was clearly a bug in the latest AE’s premultiplication handling. You could change the Interpret Footage setting on a clip between Straight or Premultiplied and the results in AE did NOT change at all, even after purging cache, etc. AE was always treating the clips as straight even when it claimed to be treating them as premultiplied. I don’t know if Adobe has patched this yet, but try exporting as Straight and see if that removes the fringe inside AE.