An image processing apparatus includes a hardware processor configured to: acquire a plurality of pieces of image information including image-capturing regions overlapping partially; to set first and second correction values with a predetermined value, the first correction value being used for correction of luminance of a first region of interest included in a first overlap region in which a first image-capturing region overlaps an adjacent second image-capturing region, the second correction value being used for correction of luminance of a second region of interest included in a second overlap region in which the first image-capturing region overlaps an adjacent third image-capturing region; and to set with the first and second correction values an individual correction value used for correction of luminance of a region between the first region of interest and the second region of interest in the first image-capturing region.