1. An image processing method comprising the steps of: extracting edges from each original image of a plurality of original images, thereby obtaining an edge image corresponding to the original image; extracting straight lines from the edge image, thereby obtaining a line image; determining extensions of the straight lines constituting the line image and setting a vanishing point based at least in part on the extensions; and obtaining a final image corresponding to each original image by processing each original image of the plurality of original images so that a position of the vanishing point of each original image of the plurality of original images matches with a position of a vanishing point of each other original image of the plurality of original images wherein, when the original image is processed so that the position of the vanishing point of the original image matches with the position of the vanishing point of each other original image, inclination of the original image is corrected so that the straight lines in the line image obtained from the original image match straight lines in a line image obtained from each other original image of the plurality of original images.