To implement non-ejection complementation processing while securing a chance for a nozzle in which an ejection failure has occurred to recover as a normal nozzle. Positional information for specifying an abnormal nozzle in which an ejection failure has occurred among a plurality of nozzles arrayed in a nozzle column is acquired and based on the positional information, input image data is converted into halftone image data. At this time, at least part of densities that are assumed to be obtained by a pixel line of the abnormal nozzle are distributed to pixels on a pixel line of a neighboring nozzle that is located in close proximity to the abnormal nozzle and in which no ejection failure has occurred so that in the halftone image data, at least in part of tones, the pixel on the pixel line of the abnormal nozzle has a density.