A method for identifying document edges collects a predetermined number scanlines of the document against a light backing and a dark backing. First-order statistics are calculated from the scanned data. A document edge is detected using the first-order statistics. ...http://www.google.com.tw/patents/US20020126899?utm_source=gb-gplus-share專利 US20020126899 - System and method for automatically detecting edges of scanned documents
