Perceptual coding of images for halftone display
A new technique is presented for coding gray-scale images for facsimile transmission and printing on a laser printer. The authors use a gray-scale image encoder so that it is only at the receiver that the image is converted to a binary pattern and printed. The conventional approach is to transmit the image in halftoned form, using entropy coding (e.g. CCITT Group 3, or JBIG). The main advantages of the new approach are that it is possible to get higher compression rates and that the receiver can tune the halftoning process to the particular printer. A perceptually based subband coding approach is used.<<ETX>>