An image processing apparatus includes a processor for restoring a pre-change image, an image which should have been originally captured, or an image approximating the same from source image data having undergone a change, such as deterioration, wherein the processor performs at least once iterative processing including generation of comparative data from arbitrary image data by utilization of change factor information data as to a factor responsible for a change in an image, comparison, with the comparative data, of source image data to be compared, generation of restored data by distribution of acquired difference data to the arbitrary image data by utilizing the change factor information data, and use of the restored data in place of the arbitrary image data, thereby iterating analogous processing; and accelerated processing for distributing a first corrected value, whose absolute value is larger than that of the difference data, in place of the difference data.