1. An image processing apparatus comprising a temporary memory means for two-dimensionally mapping and temporarily storing image data containing image region data corresponding to at least two image regions having a similar shape and stored in an image data storing means, a display means for reproducing images based on the image data stored in the temporary memory means, an interest region defining means for defining a region of interest in one of the at least two image regions having a similar shape displayed on the display means, a pixel specifying means for specifying at least one first reference pixel in the one of the at least two image regions having a similar shape and specifying a second pixel corresponding to the first reference pixel in at least one image region other than the one of the at least two image regions, a copy means for copying the region of interest defined by the interest region defining means and the at least one first reference pixel specified by the pixel specifying means, a template matching means for effecting template matching between minute region image data corresponding to a minute region containing the coordinate value of the at least one first reference pixel as a center coordinate value and minute region image data corresponding to a minute region containing the coordinate value of the at least one second reference pixel corresponding to the at least one first reference pixel as a center coordinate value, and an affine conversion means for effecting an affine conversion on image data corresponding to an outer periphery of the region of interest stored in the temporary memory means based on the result of the template matching made by the template matching means.