I am rendering a pass for a shot I am working on but am having some problems with the transparency. I am rendering the frames out as png and also tried targa but have some white artifacts around the edges of the characters. Does anyone know how to fix this as it is going to look very odd if I composit them onto the other passes and they have a white halo.
I took one of the frame into a app called pixelformer and found that when I exported it as a png the problem was fixed. Unfortunately you cant batch render with the app and I do not really want to sit around importing and exporting a thousand frames+ to fix the problem.

If anyone has any ideas or knows what I am doing wrong it would be much appreciated.

Cheers,

Leon