FACSIMILE DYNAMIC THRESHOLDING APPARATUS AND METHOD OF USE THEREOF

A facsimile system for scanning a graphic image to produce a stream of output bits representative of an m.times.n array of picture elements of the image, each output bit being corrected to compensate for the average tone of a subarray of surrounding picture elements. The average tone is measured by a count of those gray levels, representative of the picture elements of the subarray, that exceed a nominal threshold. Thus the tone of the subarray dynamically adjusts the threshold of the gray level to output bit conversion of each picture element.