indeed, normalize(NORM_MINMAX) uses a single, global min/max value.
(simply, for each pixel, subtract the global min, then divide by global (max-min))
what would that be ? some local neighbourhood ?
which is, exactly ? please explain (on a higher level) !
what’s the concept behind the min-max filter, and what do you need it for ?
i wonder, where you found that idea ? it’s for sure not the ‘general’ case.
(and would only work on binary images)