METHOD AND APPARATUS FOR HALFTONING AND INVERSE HALFTONING AND THE TRANSMISSION OF SUCH IMAGES

摘要

A method for obtaining the inverse halftone or gray scale image of a halftone image is disclosed in which the halftone image can be comprised of clustered dots or dispersed dots, and it is not necessary to have knowledge of the screening methods or parameter. This method involves adaptive run-length filtering over at least one of rows and colums and diagonals of said halftones. A method for transmitting and receiving a gray scale image in a compressed and decompressed manner, respectively, is also disclosed for efficient facsimile transmission of images. This method involves transmitting a local mean continuous tone image and an error image.