MIDDLE TONE PICTURE DISPLAY METHOD

摘要

The edge of a letter is emphasized to increase decipherability and the image data is transmitted at high speed by a dithering method which uses wave dither matrix. The method comprises the steps of: (A) scanning a manuscript by pixel unit and storing the scanned data on a buffer; (B) deciding the local brightness difference of the current scan data; (C) discriminating edge by inspecting that the brightness difference is larger than local inverse value; (D) converting half tone to white when the brightness difference is larger than local inverse value and the current pixel is brighter than local brightness and otherwise converting to black; and (E) discriminating that current pixel is not edge when local brightness difference is less than local inverse value and coding the current pixel by binary code.