Min/Max Filter (Minblur)

from vapoursynth import core

def MMFilter(clips, mode='min', planes=None):
    """ Min/Max Filter
        For "clips" supply an array of 3: a source clip and 2 filtered clips
        When mode='max' - Take the largest filtered difference, or the mean difference if one is darker and the other brighter
        When mode='min' - Take the smallest filtered difference, or the source pixel if one is darker and the other brighter
    """
    planes = list(range(clips[0].format.num_planes)) if planes is None else [planes] if isinstance(planes, int) else planes
    expr = 'x y - x z - * 0 < {} x y - abs x z - abs < {} ? ?'.format('y z + 2 /' if mode=='max' else 'x', 'z y' if mode=='max' else 'y z')
    expr = [expr if i in planes else '' for i in range(clips[0].format.num_planes)]
    return core.std.Expr(clips, expr)

# Example (MinBlur):
# clips = [clip, clip.rgvs.Removegrain(11), clip.std.Median()]
# MMFilter(clips, 'min')