Implementation for Processing.org of the Hough Transform to locate straight lines in images - as described by http://homepages.inf.ed.ac.uk/rbf/HIPR2/hough.htm
An adaptation of Olly Oechsle's algorithm - http://vase.essex.ac.uk/software/HoughTransform/
David Chatting - 4th March 2013 davidchatting.com