There is provided an image processing method in which in a full line type inkjet printer using a connecting head having an overlap region, even if a conveyance direction of a print medium is more or less inclined, a density change or degradation of graininess is not introduced. Therefore, an image data in a non-overlap region is distributed to a plurality of nozzle arrays such that ink is ejected from all the plurality of the nozzle arrays. On the other hand, a region where a print allowance rate changes in the overlap region is divided into plural regions, and the image data is distributed to the plurality of the nozzle arrays such that these regions are located to be shifted.