samples/cpp/tutorial_code/ImgTrans/houghcircles.cpp


An example using the Hough circle detector

using namespace cv ;
using namespace std ;
int main( int argc, char ** argv)
{
const char * filename = argc >=2 ? argv[1] : "smarties.png" ;
// Loads an image
// 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;
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);
return EXIT_SUCCESS;
}