I wrote exrmean because I found a way to emulate Fragmentarium-style multiple #subframe #antialiasing with #KF: render a zoom out sequence with the zoom size set to 1 (so each image shows the same location).

With jitter enabled, the pseudorandom seed for subpixel offsets is incremented each frame, so the images will be slightly different.

Averaging them all (in linear light, as used in EXR) will give a final image with higher quality than any individual frame, without having needed to render a huge image and downscale it (the previous option).

Enable "reuse reference" to avoid calculating it each subframe (unfortunately the series approximation is recalculated, which is not optimal).

Probably better than using vast amounts of temporary space for EXR files in this method would be to extend KF to do the subframe rendering itself. That'd be much more work than this quick hack though.