The Hough transform and the Radon transform are indeed very similar to each other and their relation can be loosely defined as the former being a discretized form of the latter… However, the Hough transform is a quick algorithm that can be prone to certain artifacts. Radon, being more mathematically sound, is more accurate but slower. - stack

• Radon and Hough transforms and how they relate to each other

How the Hough Transform Was Invented - [HN]

• pdf
• duality vizualizer (online)
• Fast Hough Transform

Line Detection

Circle Detection

see also

• Hitting the bullseye - a new circle detection algorithm which handles all the above issues and with robustness and accuracy.