Picture transfer method and apparatus therefor

摘要

A system for sampling binary value images of white and black and efficiently encoding and decoding them is disclosed. An image is sampled to form a plurality of small picture cells. The small picture cells are merged in groups of four to form a plurality of large picture cells. At least one least frequently occurring density level is determined for the plurality of large picture cells. The least frequently occurring density level is converted to an adjacent density level. The density levels for the picture cells are then encoded and transmitted to a receiver. At the receiving end, the encoded large picture cells are decoded to form a plurality of restored large picture cells. Each restored large picture cell is divided into four small restored picture cells by comparing its density level with that of four neighboring large restored picture cells.