The invention is a method and apparatus for reducing noise in an image.
The method and apparatus involves calculating a plurality of directional
operators, comparing the directional operators to a predetermined
threshold, and applying a filter responsive to the comparing. The method
and apparatus computes the directional operators by taking a weighted sum
of the absolute differences between a target pixel and its surrounding
pixels. The comparison signals to the method or apparatus the existence
of a line or edge. If the method or apparatus detects no edge or line,
the method applies a smoothing or averaging filter. If the method or
apparatus detects an edge or line, the method applies a median filter in
the direction with a minimum directional difference.