A method of stitching an image to combine at least a first image and a second image in a digital image processing apparatus includes obtaining matching areas of the first image and the second image where the second image overlaps the first image, and changing gradations of an entire area of the second image to make a representative gradation of the matching area of the first image the same as a representative gradation of the matching area of the second image, wherein a change rate in changing at least one of the gradations of the entire area of the second image is set according to a level of a gradation of the second image before the changing the gradations of the entire area of the second image.