US Patent 8979238 Image processing method and image processor

Provided are an inkjet printing apparatus and inkjet printing method that can, regardless of an ejection frequency of a print head, stabilize density of an image expressed on a print medium. For this purpose, an ink concentration integrated value is obtained according to the ejection history of each nozzle so as to be increased by data indicating non-ejection of the nozzle or decreased by data indicating ejection. Then, image data on the target pixel is corrected such that density of the target pixel is further reduced as the pixel is subjected to printing by a nozzle having a higher ink concentration integrated value.