What is the math behind the AA of ID mask node?

I was wondering what is the math behind the anti-aliasing filter of the ID mask node?

It’s not just a blur, the result is more accurate. How can I do it from scratch? It can be usefull in other situations.

Thanks :slight_smile:

Unless you select Full Sample and turn the AA filter size down as low as it will go, you’re not going to get a good AA on the ID mask because the check box on the node AA function is fairly crude (low sample rate and clips some parts of image).

ID Mask AA: http://www.blender.org/development/release-logs/blender-243/composite-uv-map-displace-id-mask-and-z-combine/

FSAA: http://www.blender.org/development/release-logs/blender-246/rendering-features/