I'm trying to get an accurate index pass for compositing. My geometry (a window in this case) consists of straight lines and it would be nice to have a perfect mask for color correction. As you can see Anti-Aliasing is enabled, but there are still some weird pixels:
Until now my workaround was to blur the image, but in this case straight lines are key to work with. How to achieve this? Is there a render setting to prevent the noise or make it less noisy?