Inigo Quilez has written a tiny bit on something he calls 'variance-based blur' which seems to do something similar. See the last section of https://www.iquilez

Inigo Quilez has written a tiny bit on something he calls 'variance-based blur' which seems to do something similar. See the last section of https://www.iquilezles.org/www/articles/wavelet/wavelet.htm https://www.iquilezles.org/www/articles/wavelet/wavelet.htm