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      1 /********************************************************************************
      2 *
      3 *
      4 *  This program is demonstration for ellipse fitting. Program finds
      5 *  contours and approximate it by ellipses.
      6 *
      7 *  Trackbar specify threshold parametr.
      8 *
      9 *  White lines is contours. Red lines is fitting ellipses.
     10 *
     11 *
     12 *  Autor:  Denis Burenkov.
     13 *
     14 *
     15 *
     16 ********************************************************************************/
     17 #include "opencv2/imgproc/imgproc.hpp"
     18 #include "opencv2/imgcodecs.hpp"
     19 #include "opencv2/highgui/highgui.hpp"
     20 #include <iostream>
     21 using namespace cv;
     22 using namespace std;
     23 
     24 // static void help()
     25 // {
     26 //     cout <<
     27 //             "\nThis program is demonstration for ellipse fitting. The program finds\n"
     28 //             "contours and approximate it by ellipses.\n"
     29 //             "Call:\n"
     30 //             "./fitellipse [image_name -- Default ../data/stuff.jpg]\n" << endl;
     31 // }
     32 
     33 int sliderPos = 70;
     34 
     35 Mat image;
     36 
     37 void processImage(int, void*);
     38 
     39 int main( int argc, char** argv )
     40 {
     41     const char* filename = argc == 2 ? argv[1] : (char*)"../data/stuff.jpg";
     42     image = imread(filename, 0);
     43     if( image.empty() )
     44     {
     45         cout << "Couldn't open image " << filename << "\nUsage: fitellipse <image_name>\n";
     46         return 0;
     47     }
     48 
     49     imshow("source", image);
     50     namedWindow("result", 1);
     51 
     52     // Create toolbars. HighGUI use.
     53     createTrackbar( "threshold", "result", &sliderPos, 255, processImage );
     54     processImage(0, 0);
     55 
     56     // Wait for a key stroke; the same function arranges events processing
     57     waitKey();
     58     return 0;
     59 }
     60 
     61 // Define trackbar callback functon. This function find contours,
     62 // draw it and approximate it by ellipses.
     63 void processImage(int /*h*/, void*)
     64 {
     65     vector<vector<Point> > contours;
     66     Mat bimage = image >= sliderPos;
     67 
     68     findContours(bimage, contours, RETR_LIST, CHAIN_APPROX_NONE);
     69 
     70     Mat cimage = Mat::zeros(bimage.size(), CV_8UC3);
     71 
     72     for(size_t i = 0; i < contours.size(); i++)
     73     {
     74         size_t count = contours[i].size();
     75         if( count < 6 )
     76             continue;
     77 
     78         Mat pointsf;
     79         Mat(contours[i]).convertTo(pointsf, CV_32F);
     80         RotatedRect box = fitEllipse(pointsf);
     81 
     82         if( MAX(box.size.width, box.size.height) > MIN(box.size.width, box.size.height)*30 )
     83             continue;
     84         drawContours(cimage, contours, (int)i, Scalar::all(255), 1, 8);
     85 
     86         ellipse(cimage, box, Scalar(0,0,255), 1, LINE_AA);
     87         ellipse(cimage, box.center, box.size*0.5f, box.angle, 0, 360, Scalar(0,255,255), 1, LINE_AA);
     88         Point2f vtx[4];
     89         box.points(vtx);
     90         for( int j = 0; j < 4; j++ )
     91             line(cimage, vtx[j], vtx[(j+1)%4], Scalar(0,255,0), 1, LINE_AA);
     92     }
     93 
     94     imshow("result", cimage);
     95 }
     96