HALFTONING METHOD AND APPARATUS

摘要

The present invention relates to halftoning images for subsequent transmission. In particular, the invention is a halftoning method and system suitable for halftoning images which are to undergo run length encoding, such as in facsimile transmission. The invention processes the digital words to increase the number of pixels that are fully black and fully white. Then the invention error diffuses the pixels using error coefficients which govern the proportion of the error for each pixel that is distributed to other pixels on the same and following lines. The error coefficient for at least one of the pixels of the current line is reduced, and the error coefficient for at least one of the pixels of the next following line is increased, such that should the error diffused pixels be compressed by run length encoding (where a run of identical symbols is replaced by a symbol and a count) the efficiency of the compression is improved.