matte objects and exponential colour mapping

[super gnu]

i have a camera tracked scene with a video background, and some mattes to drop shadows onto it around the edges of my scene.

trying out exponential colour mapping (and exponential hsv) and im loving the warm lighting i can get. far better than my earlier linear efforts.

however, if i have "affect background" unticked, the background is still affected thru the mattes, resulting in dark patches wherever a matte object is.

the obvious thing would be to either use a black background and then overlay over the background in the comp afterwards, or tick "affect background" so that the bg is darkened by the same amount as the mattes.

unfortunately this gives me real problems, since when i "premultiply with black" to remove the crappy edges in the comp, it screws up several other aspects of my composite. (i could explain but it would take even more words..)

so i cant do that really.

anyone know how to fix this problem? really dont want to have to go back to linear colour mapping.

[super gnu]

no suggestions? has no one else had problems with exponentioal exposure and matte objects?

[RErender]

I would normally composite the background in separately.

[olly]

I'm having this problem as well, using vray 1.5.00.

It's fine to comp a background in, in post, but what about previewing renders in max as you work?

Thanks,
Olly

[vlado]

There is currently no way around this; when V-Ray has to make a decision whether to apply color mapping or not, it doesn't know what particular shader an object has - just that there is some object, or not...

Best regards,
Vlado