Patent ID: 8328310

Claim:
An ink jet printing apparatus for printing an image on a print medium by ejecting ink from a print head in which a plurality of nozzles are arrayed in a predetermined direction so as to form a nozzle array comprising: a conveying unit configured to convey the print medium relative to the print head a distance corresponding to a width of one of a plurality of nozzle blocks that are formed by dividing the nozzle array in the predetermined direction, and a printing unit configured to form an image in a region corresponding to one of the nozzle blocks on the print medium by a plurality of movements of the print head, each of the movements being performed according to a print permission ratio predetermined for individual nozzles in the plurality of nozzle blocks, the print permission ratio being a ratio of the number of those pixels that are permitted to be printed by each nozzle in one movement of the print head to a total number of pixels making up an area over which the nozzle passes in one movement of the print head, wherein the print permission ratios are set such that the print permission ratios corresponding to nozzles in a non-boundary section of the first nozzle block is a substantively constant first ratio, the print permission ratios corresponding to nozzles in a non-boundary section of the second nozzle block adjoining to the first nozzle block is a substantively constant second ratio that is larger than the first ratio, and the print permission ratios corresponding to nozzles in a boundary section of the first nozzle block and the second nozzle block increase progressively from the first ratio to the second ratio according to a location of nozzle in the predetermined direction from a side of the first nozzle block to a side of the second nozzle block.