Spatial noise is reduced in an image having a plurality of pixels by
detecting object boundaries and unstructured areas in the image and
applying 3-tap high pass filters to each pixel in the image in at least
four, but less than eight directions to determine the best direction for
local low pass filtering. Low pass filtering is applied only along object
boundaries and unstructured areas within the image so as to minimize the
tendency to blur image edges. Using only four high pass filters to locate
horizontal, vertical and diagonal image edges passing through the center
of a 3.times.3 pixel array provides good results.