PURPOSE: To obtain a binary picture having high picture quality, by inputting a picture signal in advance at a binary-coding circuit of a shaded picture, and calculating a binary-coded threshold value by data near picture elements and comparing the calculated value with the input picture signal for binary coding.

CONSTITUTION: In binary coding a picture element 2a, the binary data of a picture element 2b finished for the processing is used for binarycoding. A picture signal obtained from a contrast picture from raster scanning enters a comparator 11. The binary output is obtained by comparing the signal with the data in a threshold circuit 12. A part of the output is stored at a line buffer 13 temporarily. The binary data of the 12 pieces of picture elements 2b near the picture element 2a is inputted for address and the binary-coded threshold data corresponding to the value is read out at an ROM14. The data is converted into an analog signal at a D/A converter 15 and fed to a comparator 11 as the threshold data.