1. An image processing method comprising: acquiring a read image obtaining by a reading of an original; extracting broken lines from the read image of the original, wherein the broken lines are extracted from an image of an irregular cut side in the read image of the original; determining whether the extracted broken lines have a predetermined repetitive pattern for determining a contour of the original; and in a case where the broken lines have the predetermined repetitive pattern, specifying an area corresponding to the original from the read image based on the broken lines.