An image processing apparatus 101 that generates output image data based on multi-level image data is provided with an error diffusion processing unit 104 that generates tone pixel data from the pixel-of-interest data according to an error diffusion method, a dither processing unit 103 that generates tone pixel data from the pixel-of-interest data according to a dither processing method, an allotment ratio determination unit 105 that increases the allotment ratio with respect to the error diffusion method as the difference between the maximum density and the minimum density increases, and a composition unit 109 that composites the tone pixel data for a pixel of interest that has been generated by the error diffusion processing unit 104 and the dither processing unit 103 according to the allotment ratios determined by the allotment ratio determination unit 105, and outputs the composited data as pixel data of the output image data.