I will take the opportunity to call out one of my favourite libraries, BoofCV (http://boofcv.org http://boofcv.org) It comes with a wonderful demonstration too

I will take the opportunity to call out one of my favourite libraries, BoofCV (http://boofcv.org http://boofcv.org) It comes with a wonderful demonstration tool that allows you to apply the various included algorithms to images and tweak the parameters in real-time – including the Hough transform. A great tool for helping to understand how these kinds of algorithms work!