说明：  Hough变换对圆的检测 Hough变换的基本原理在于，利用点与线的对偶性，将图像空间的线条变为参数空间的聚集点，从而检测给定图像是否存在给定性质的曲线。
(Hough transform for circle detection Hough transform basic principle is that the use of point and line duality, the image space into a parameter space of lines gather, thus detecting the existence of a given image given the nature of the curve.)