Error diffusion with dynamically adjusted kernel

Error diffusion is a method for generating high quality bi-level images from continuous tone images. It is well known that certain objectionable patterning artifacts can occur in error diffused images. The author considers a method for adjusting the error diffusion kernel dynamically so that a local frequency weighted square error criterion is minimized. It can be shown that such an error criterion can be expressed as a linear function of the error diffusion filter. One can then use, for example, the LMS algorithm to adjust the filter coefficients concurrently with the halftoning process so that the distortion is minimized. Such an algorithm produces better halftone image quality compared to traditional error diffusion with a fixed filter.<>