An image processing apparatus includes an image input device to convert image data into uncompressed data of CMYK, a gradation processing device to perform a gradation process on the uncompressed data to generate a halftone image, a rearrangement determination device to determine necessity of rearrangement of pixels of the halftone image, a selector to select an output destination based on a rearrangement necessity determination result, a rearrangement device to rearrange the pixels by using a threshold table used at a time of execution of the gradation process of the halftone image, and a coding device to output data obtained by coding data of the halftone image. According to the image processing device, coding efficiency can be improved more than in the related art while a harmful effect (reduction in code amount) due to the rearrangement process is suppressed.