ハフ変換
http://www.cs.tu-bs.de/rob/lehre/bv/Hough.html - Java Applet + Source for learning the Hough transformation in slope-intercept form
http://www.cs.tu-bs.de/rob/lehre/bv/HNF.html - Java Applet + Source for learning the Hough-Transformation in normal form
http://homepages.inf.ed.ac.uk/rbf/HIPR2/hough.htm