This function sets each pixel in the destination image as the
median value of all the input pixel values taken in the neighborhood of the
processed pixel. The neighborhood is determined by the fixed square mask of the 3x3
size with the anchor cell as the center cell of the mask. The parameter
specifies the weight of
the processed pixel, that is how many times its value is included into calculations.
The value of this parameter should be odd. If it is even, the function changes its
value to the nearest less odd number and returns the warning message.