Fast Circle Detection Using Gradient Pair Vectors

The Circle Hough Transform (CHT) has become a common method for circle detection in numerous image processing applications. Because of its drawbacks, various modifications to the basic CHT method have been suggested. This paper presents an algorithm to find circles which are totally brighter or darker than their backgrounds. The method is size-invariant, and such circular shapes can be found very fast and accurately. Though Fast Circle Detection (FCD) method loses the generality of the CHT, we show that there are many applications that can use this method after a simple preprocessing and gain a considerable improvement in performance against the CHT or its modified versions. This method has been evaluated in some famous industrial and medical fields, and the results show a significant improvement of finding circular shape objects.