1. A system for producing a line drawing, comprising in combination: (a) apparatus for processing a sampled video signal to produce a digital signal comprising a plurality of bits wherein each sampling point of the video signal is represented by a single bit digit digital signal; (b) means for storing a predetermined number of said single bit digital signals to produce a data matrix, said data matrix comprising a predetermined number of sample points; (c) means for comparing a selected element of said data matrix to a predetermined number of other elements of said data matrix to determine if the quality of said line drawing can be improved by changing the value of said selected element; and (d) means for selectively changing said selected element to improve the quality of said line drawing.