houghcircles.cpp

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "openCVUtils.h"
#include <iostream>

using namespace cv;
using namespace std;

static Mat _inImage;
static Mat _outImage;


static void help()
{
    cout << "\nThis program demonstrates circle finding with the Hough transform.\n"
            "Usage:\n"
            "./houghcircles <image_name>, Default is pic1.png\n" << endl;
}

static  const char* keys =
{
    "{1| |circle.800.jpg|input image file}"
};


int houghcircles(int argc, char** argv)
{
    CommandLineParser parser(argc, argv, keys);
    string filename = parser.get<string>("1");
    filename = assetPath(filename.c_str());

    

    Mat img = imread(filename, 0);
    if(img.empty())
    {
        help();
        cout << "can not open " << filename << endl;
        return -1;
    }

    Mat cimg;
    medianBlur(img, img, 5);
    cvtColor(img, cimg, COLOR_GRAY2BGR);

    vector<Vec3f> circles;
    HoughCircles(img
                 , circles
                 , CV_HOUGH_GRADIENT //method – Detection method to use. Currently, the only implemented method is CV_HOUGH_GRADIENT , which is basically 21HT , described in [Yuen90].
                 , 1 //p – Inverse ratio of the accumulator resolution to the image resolution. For example, if dp=1 , the accumulator has the same resolution as the input image. If dp=2 , the accumulator has half as big width and height.
                 , 60  //minDist – Minimum distance between the centers of the detected circles. If the parameter is too small, multiple neighbor circles may be falsely detected in addition to a true one. If it is too large, some circles may be missed.
                 ,
                 100 //cannyThreshold – The higher threshold of the two passed to the gpu::Canny() edge detector (the lower one is twice smaller).
                 , 30 //votesThreshold – The accumulator threshold for the circle centers at the detection stage. The smaller it is, the more false circles may be detected.
                 , 250 //minRadius – Minimum circle radius.
                 , 300 // change the last two parameters
                 //maxRadius – Maximum circle radius.
                 //maxCircles – Maximum number of output circles.
                // buf – Optional buffer to avoid extra memory allocations (for many calls with the same sizes).
                                // (min_radius & max_radius) to detect larger circles
                 );
    for( size_t i = 0; i < circles.size(); i++ )
    {
        Vec3i c = circles[i];
        circle( cimg, Point(c[0], c[1]), c[2], Scalar(0,0,255), 3, CV_AA);
        circle( cimg, Point(c[0], c[1]), 2, Scalar(0,255,0), 3, CV_AA);
    }

    imshow("detected circles", cimg);
    waitKey();

    return 0;
}