To provide an image processing method and an image processing apparatus for allowing an error to be substantially accurately propagated at joints of blocks even when image data are divided into a plurality of blocks and each of them is subjected to an error diffusion processing simultaneously.

The image processing method and image processing apparatus comprise image data dividing means for dividing image data into a plurality of regions, divided error diffusing means for performing error diffusion processing for each divided region that was divided by the image data dividing means, virtual error generating means for generating a virtual error before starting of the divided error diffusing means, enlarged error diffusion processing means for enlarging an error matrix so as to use errors generated by adjacent divided error diffusing means, thus making it possible to obtain an effect that an error can substantially accurately be propagated at joints of blocks even when image data are divided into a plurality of blocks with each of them being subjected to the error diffusion processing simultaneously.