Patent ID: 7525690

Claim:
An image processor for generating image regeneration output data from grayscale input data, comprising: a halftone processing unit which converts said grayscale input data into said image regeneration output data corresponding to a dot size of pixels; and a lookup table to be referred to by said halftone processing unit, including a plurality of gamma tables storing image regeneration output data corresponding to said grayscale input data, corresponding to the position of the pixels of grayscale input data, wherein, in said lookup table, virtual representative gamma tables are respectively allocated to identical index pixel groups, each identical index pixel group being disposed on predetermined displacement vectors, wherein, for each virtual representative gamma table allocated to a corresponding identical index pixel group, a plurality of diffusion gamma tables are dispersed on the predetermined displacement vectors of the corresponding identical index pixel group, and wherein said plurality of diffusion gamma tables have the image regeneration output data near an output grayscale value of said virtual representative gamma table determined according to the grayscale input data.