Error diffusion using next scanline error impulse response

摘要

An apparatus ( 1100 ) for halftoning an image is disclosed. The apparatus comprises means for determining an output value of a current pixel on a current scanline using a sum of an input value ( 1102 ) for the current pixel and a neighborhood error value ( 1150 ) at the current pixel, means ( 1124 ) for determining an error at the current pixel as the difference between (i) the sum of the input value ( 1102 ) for the current pixel and the neighborhood error value ( 1150 ) at the current pixel, and (ii) the output value ( 1120 ) of the current pixel; and means ( 1140 ) for adding a proportion of the error at the current pixel to neighborhood error values at as yet unprocessed pixels of a subsequent scanline in accordance with a next scanline error impulse response; wherein said next scanline error impulse response approximates a function which spreads with self-convolution in proportion to a degree of self-convolution.