Patent ID: 7614713

Claim:
A data processing method for generating image data which is used for plural printing scans of first and second nozzle groups for ejecting ink, relative to a predetermined area of a print medium, said method comprising: a first dividing step of dividing image data to be printed on the predetermined area by the first nozzle group into a plurality of image data used for the plural printing scans, by using a first pattern group having plural mask patterns corresponding to the plural printing scans; and a second dividing step of dividing image data to be printed on the predetermined area by the second nozzle group into a plurality of image data used for the plural printing scans, by using a second pattern group having plural mask patterns corresponding to the plural printing scans, wherein an arrangement of print permitting pixels in one mask pattern, of the first pattern group, which is used for a predetermined printing scan of the plural printing scans, is different from an arrangement of print permitting pixels in one mask pattern, of the second pattern group, which is used for the predetermined printing scan, and low frequency components of an arrangement pattern of print permitting pixels obtained by a logical product of the one mask pattern of the first pattern group and the one mask pattern of the second pattern group based on a correspondence relationship of the two mask patterns when the two mask patterns are used are fewer than that obtained by a logical product of the one mask pattern of the first pattern group and the one mask pattern of the second pattern group based on a correspondence relationship different from the correspondence relationship of the two mask patterns when the two mask patterns are used.