Patent ID: 6930800

Claim:
A halftone generation system for generating halftone data of a pixel based on comparison between multilevel image data of the pixel and threshold matrix data, said halftone generation system comprising: threshold matrix data storage means for storing threshold matrix data; threshold data read means for reading all threshold data applied to halftone data generation processing for one scanning line from said threshold matrix data storage means; first register means for retaining all the read threshold data applied to halftone data generation processing for the scanning line; threshold data selection means for selecting a plurality of threshold data pieces from among all the threshold data pieces applied to halftone data generation processing for the scanning line retained in said first register means and outputting the selected threshold data pieces; and a plurality of comparison means for performing comparison processing between the threshold data pieces selected by said threshold data selection means and multilevel image data of a plurality of pixels in parallel and executing parallel generation processing of halftone data of the pixels, wherein said threshold data selection means comprises as many selector circuits as the number of halftone data pieces generated in parallel in said plurality of comparison means, and input of each of said selector circuits is connected to output of said first register means at intervals of as many as the number of halftone data pieces generated in parallel in said plurality of comparison means, and output of each of the selector circuits is switched in response to the pixel position of halftone data generated in parallel.