samples/cpp/tutorial_code/ImgTrans/houghcircles.cpp

ハフ円検出器を使用した例

 
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
 
using namespace cv;
using namespace std;
 
int main(int argc, char** argv)
{
 const char* filename = argc >=2 ? argv[1] : "smarties.png";
 
 // Loads an image
 Mat src = imread( samples::findFile( filename ), IMREAD_COLOR );
 
 // Check if image is loaded fine
 if(src.empty()){
        printf(" Error opening image\n");
        printf(" Program Arguments: [image_name -- default %s] \n", filename);
 return EXIT_FAILURE;
    }
 
 Mat gray;
    cvtColor(src, gray, COLOR_BGR2GRAY);
 
    medianBlur(gray, gray, 5);
 
    vector<Vec3f> circles;
    HoughCircles(gray, circles, HOUGH_GRADIENT, 1,
                 gray.rows/16,  // change this value to detect circles with different distances to each other
                 100, 30, 1, 30 // change the last two parameters
 // (min_radius & max_radius) to detect larger circles
    );
 
 for( size_t i = 0; i < circles.size(); i++ )
    {
 Vec3i c = circles[i];
 Point center = Point(c[0], c[1]);
 // circle center
        circle( src, center, 1, Scalar(0,100,100), 3, LINE_AA);
 // circle outline
 int radius = c[2];
        circle( src, center, radius, Scalar(255,0,255), 3, LINE_AA);
    }
 
    imshow("detected circles", src);
    waitKey();
 
 return EXIT_SUCCESS;
}