public class ThresholdMedianSmoother
Do a median smoothing for all pixels that differ from the median by
more then the threshold
Size gives the size of the box in which the median is computed
This must be an odd integer >= 3
Threshold is the change beyond which the pixel will be smoothed
Assumed to be 0 if omitted which means that all pixels are smoothed.
If specified then the threshold will be computed as a ratio of the
current and median values. E.g., if specified and threshold is 2 then
Pixels <0.5 or >2.0 times the median value will be smoothed.
If specified should have the single character values + or - which
indicates that only only values greater than or less than the median
will be considered for smoothing.