Smoother object index pass.

Is it possible to get a smoother Object Index pass? I needed it to use as a mask for color correction but noticed the edges were very rough.

Example:
http://img72.imageshack.us/img72/5459/obindex.png

Unfortunately the Index passes aren’t antialiased. The ID Mask node has that “Smooth Mask” button but it’s just interpolation to blur the edges.

You can always render your ID pass in larger resolution (two times bigger for example) and scale it down in composer.