A coarse-to-fine approach for circle detection

An efficient circle detection method using a coarse-to-fine strategy is proposed. The Hough transform is performed using a rough Hough space within a small window around a feature point which is selected using local connectivity information. Hough cells which have sufficient number of votes are retained, whilst all others are discarded. These Hough cells are refined using a finer quantization and then a larger window around the feature point is employed for another Hough transform. This process is repeated till sufficient evidence for the existence of a circle is obtained