BINARY CODING SYSTEM

A binary-coding device for a raster picture scanner is herein disclosed in which the miscoding produced by various states in adjacent picture elements is eliminated. The device comprises a comparator which compares the analog picture signal of the scanner with a reference voltage. A "black-or-white" state of a first picture element adjacent to the n.sub.th, i.sub.th picture element to be read (the first picture element being on the i.sub.th subscanning line) is stored in an addressable RAM, and the state of a second picture element adjacent to the n.sub.th, i.sub.th picture element to be read (the second picture element being on the n.sub.th main scanning line) is inputted to a flipflop. The states of the two adjacent picture elements are compared in a plurality of dissimilar logic gates which output a signal indicative of the reference voltage which should be used in order to maximize accurate coding. These signals are applied to a plurality of switches which output the desired reference voltage. In a second embodiment, a multiplexer controls the switching between a plurality of comparators, each of which has a different reference voltage.