Gamma 2.2, Motion Blur, Alpha problem

[DanielWichterich]

I guess it is some well known problem and hopefully easy to solve:
Max Gamma setting is set to 2.2, I render something with camera motion blur and save it as a not floating point image (let's say rpf 16bit). When I import it in After Effects I get an white aura at the alpha edge. It's rendered on black and AE is told to interpret it as premultiply black.
Thanks in advance!
Daniel

[Zdravko]

Can you attach a screenshot of the issue or a simple scene?

[DanielWichterich]

ok I made some tests: the mblur is not the reason for that, it is just making the effect more visible. problem seems to be I got a strong blueish color in the gi environment slot. then put on a grey backrground a white rim becomes visible.


here is the file to that
https://dl.dropbox.com/u/12432599/vray_alpha.max

[Dariusz Makowski (Dadal)]

Long shot, is ur alpha unpremultiplied/premultiplied?

Does it happens with other file formats/jpg/png/etc?

[DanielWichterich]

when rendering a straight alpha i am getting a clean result. and i think this has nothing to do with vray as it is the same with scanline. seems like when gamma is set to 2.2 I HAVE to render straight to get a clean alpha. wonder why i never had that problem before... here you can see that more clearly with motionblur

[Dariusz Makowski (Dadal)]

Humh, interesting...

[trixian]

I am having this issue too. Not too long ago this was not a problem, as I ALWAYS render premultiplied on ablack bg. I suspect its from one of the max patches or such. This happens with float exr's too......that is afaik, all formats get this issue.