Patent ID: 8422080

Claim:
An image processing apparatus that generates output image data based on multi-level image data, comprising: a calculation unit configured to calculate a maximum density and a minimum density in a pixel block that includes pixel-of-interest data in the multi-level image data and that is constituted from a prescribed number of pixels; an error diffusion processing unit configured to generate tone pixel data from the pixel-of-interest data according to an error diffusion method; a dither processing unit configured to generate tone pixel data from the pixel-of-interest data according to a dither processing method; an allotment ratio determination unit configured to determine an allotment ratio of the error diffusion method and an allotment ratio of the dither processing method based on the maximum density and the minimum density that have been calculated by the calculation unit; a composition unit configured to composite the tone pixel data for a pixel of interest that has been generated by the error diffusion processing unit and the dither processing unit according to the allotment ratios determined by the allotment ratio determination unit, and output the composited data as pixel data of the output image data, wherein the allotment ratio determination unit increases the allotment ratio with respect to the error diffusion method as a difference between the maximum density and the minimum density increases; an image forming unit configured to form an image on a recording medium based on the pixel data generated by the composition unit; and a minimum density compensation unit configured to, in a case in which a value of the pixel data for the pixel of interest outputted by the composition unit is smaller than a minimum density value with which the image forming unit can perform formation, feed back the value of the pixel data to the error diffusion processing unit as an error to be allotted to a next pixel, and also output 0 as a density value of the pixel data.