Translation of an input pixel value to an output pixel value using error diffusion and variable thresholds

摘要

A diffusion filter generates diffused pixel value of gray scale image (11) by adding diffused error to the input pixel value. A feedback modulator generates threshold value of current pixel using previous output pixel value which occurred at predetermined pixels. A quantizer selects an pixel value of half tone binary image (22) by comparing the diffused pixel value to the threshold value of gray scale image.