For the purpose of providing an image processing method for properly performing filtering, a local region is defined containing a pixel of interest in an original image (504); pixel groups are defined in the region in a plurality of modes (506); a pixel group mode which best fits a structure of the original image in the local region is selected (508, 510); and an average pixel value of the pixel group which contains the pixel of interest is used as a new pixel value for the pixel of interest.