Two tone and multiple image discrimination and signal binarization system

Claim 1

A picture signal binarization system for converting both multiple-tone portions and two-tone portions of an image into picture signals of accurate graylevels comprising: operation means for computing the mean density value of points in a predetermined range around a particular point of an image to be binarized; first determination means operatively connected to said operation means for determining whether or not the density value of the particular point is larger than a first value, said first determination means including first comparator means for comparing an output of the first determination means with an output from the operation means; second determination means operatively connected to said operation means for determining whether or not the density value of the particular point is smaller than a second, said second determination means including a second comparator means for comparing an output from the second determination means with an output from the operation means; a first delay circuit operatively connected to said first comparator for delaying the output of said first comparator; a first pattern comparison circuit operatively connected to said first delay circuit; a second delay circuit operatively connected to said second comparator for delaying the output of said second comparator; a second pattern comparison circuit operatively connected to said second delay circuit; a third comparator operatively connected to said operation means for comparing the mean density value from the operation means with another value; and a third delay circuit operatively connected to said third comparator.