1. A method comprising: acquiring a read image corresponding to an original plate on which an original is placed, the read image being generated by reading of the original plate by a reading apparatus; detecting an object area corresponding to an object included in the read image acquired by the acquiring, and inclination of the object area with respect to the read image; determining a minimum rectangular area which includes the object area detected by the detecting, and is surrounded with four sides parallel to four sides of the read image respectively; specifying a pixel group included in the four sides of the minimum rectangular area determined by the determining, the pixel group constituting an edge including in the read image; and determining the minimum rectangular area as an area of the original if the pixel group specified by the specifying includes a larger number of pixels than a predetermined number or if the inclination is smaller than a predetermined inclination, wherein the inclination is detected by rotating a circumscribed rectangle which is circumscribed by the object area, and an inclination of the rotated circumscribed rectangle of which a size is smaller than a predetermined size, is detected as the inclination of the object area.