Apply a median filter to the input array using a local window-size
given by kernel_size (must be odd).
Parameters :
input : array_like
A 2-dimensional input array.
kernel_size : array_like, optional
A scalar or a list of length 2, giving the size of the
median filter window in each dimension. Elements of
kernel_size should be odd. If kernel_size is a scalar,
then this scalar is used as the size in each dimension.
Default is a kernel of size (3, 3).
Returns :
out : ndarray
An array the same size as input containing the median filtered
result.