1#include "opencv2/imgcodecs.hpp"
2#include "opencv2/highgui/highgui.hpp"
3#include "opencv2/imgproc/imgproc.hpp"
4
5#include <iostream>
6
7using namespace cv;
8using namespace std;
9
10static void help()
11{
12    cout << "\nThis program demonstrates circle finding with the Hough transform.\n"
13            "Usage:\n"
14            "./houghcircles <image_name>, Default is ../data/board.jpg\n" << endl;
15}
16
17int main(int argc, char** argv)
18{
19    const char* filename = argc >= 2 ? argv[1] : "../data/board.jpg";
20
21    Mat img = imread(filename, 0);
22    if(img.empty())
23    {
24        help();
25        cout << "can not open " << filename << endl;
26        return -1;
27    }
28
29    Mat cimg;
30    medianBlur(img, img, 5);
31    cvtColor(img, cimg, COLOR_GRAY2BGR);
32
33    vector<Vec3f> circles;
34    HoughCircles(img, circles, HOUGH_GRADIENT, 1, 10,
35                 100, 30, 1, 30 // change the last two parameters
36                                // (min_radius & max_radius) to detect larger circles
37                 );
38    for( size_t i = 0; i < circles.size(); i++ )
39    {
40        Vec3i c = circles[i];
41        circle( cimg, Point(c[0], c[1]), c[2], Scalar(0,0,255), 3, LINE_AA);
42        circle( cimg, Point(c[0], c[1]), 2, Scalar(0,255,0), 3, LINE_AA);
43    }
44
45    imshow("detected circles", cimg);
46    waitKey();
47
48    return 0;
49}
50