I've found sorting-network-based filters to be faster than these methods up to size 25x25 or so. It has worse computational complexity, but filters up to that s

I've found sorting-network-based filters to be faster than these methods up to size 25x25 or so. It has worse computational complexity, but filters up to that size covers a lot of ground in practice. See Figure 10 in https://andrew.adams.pub/fast_median_filters.pdf https://andrew.adams.pub/fast_median_filters.pdf