Patent ID: 8025352

Claim:
An ink jet printing apparatus for performing a bidirectional printing for printing an image on a print medium by ejecting ink from a print head in which a plurality of nozzles is arranged during forward and backward movements of the print head, said apparatus comprising: an executing unit for executing at least a first print mode for performing the bidirectional printing in accordance with a first mask pattern by M movements, where M is an odd number equal to 3 or more, between which movements the print medium is conveyed by a first conveying distance smaller than a length of a region on which the plurality of nozzles is arranged, and a second print mode for performing the bidirectional printing in accordance with a second mask pattern by N movements, N is an odd number larger than M, between which movements the print medium is conveyed by a second conveying distance smaller than the first conveying distance, wherein a difference between a maximum value and a minimum value of print permitted ratios, defined by the first mask pattern, for the M movements is larger than a difference between a maximum value and a minimum value of print permitted ratios, defined by the second mask pattern, for the N movements.