霍夫圆

        Mat src, dst;
	src = imread("D:/vcprojects/images/circle.png");
	if (!src.data) {
		printf("could not load image...\n");
		return -1;
	}
	char INPUT_TITLE[] = "input image";
	char OUTPUT_TITLE[] = "hough circle demo";
	namedWindow(INPUT_TITLE, CV_WINDOW_AUTOSIZE);
	namedWindow(OUTPUT_TITLE, CV_WINDOW_AUTOSIZE);
	imshow(INPUT_TITLE, src);

	// 中值滤波
	Mat moutput;
	medianBlur(src, moutput, 3);
	cvtColor(moutput, moutput, CV_BGR2GRAY);

	// 霍夫圆检测
	vector<Vec3f> pcircles;
	HoughCircles(moutput, pcircles, CV_HOUGH_GRADIENT, 1, 10, 100, 30, 5, 50);
	src.copyTo(dst);
	for (size_t i = 0; i < pcircles.size(); i++) {
		Vec3f cc = pcircles[i];
		circle(dst, Point(cc[0], cc[1]), cc[2], Scalar(0, 0, 255), 2, LINE_AA);
		circle(dst, Point(cc[0], cc[1]), 2, Scalar(198, 23, 155), 2, LINE_AA);
	}
	imshow(OUTPUT_TITLE, dst);