DITHERING METHODS FOR COLOR IMACES SUITABLE FOR RUN-LENGTH CODING

摘要

This paper describes dithering methods of color images directly applicable to run length coding.One of the typical dither matrices,the pseudo screening type matrix,is selected.By changing the positions or phases of the dither matrix elements,dithered color images can be compressed without noticeable degradation of image quality.The simulation results show that the run-length entropies and MH coding bits of the proposed pseudo screening method are less than those of the conventional one by 37 percent and 23 percent respectively.Other advantages of the proposed pseudo screening method are that the receiver can obtain a rough image at an earlier stage of transmission because the medium threshold group which is transmitted first has much color information in a single run,and that the printed image is of good quality because the primary color signals seldom overlap one another.