1 /** 2 * @function findContours_Demo.cpp 3 * @brief Demo code to find contours in an image 4 * @author OpenCV team 5 */ 6 7 #include "opencv2/imgcodecs.hpp" 8 #include "opencv2/highgui/highgui.hpp" 9 #include "opencv2/imgproc/imgproc.hpp" 10 #include <iostream> 11 #include <stdio.h> 12 #include <stdlib.h> 13 14 using namespace cv; 15 using namespace std; 16 17 Mat src; Mat src_gray; 18 int thresh = 100; 19 int max_thresh = 255; 20 RNG rng(12345); 21 22 /// Function header 23 void thresh_callback(int, void* ); 24 25 /** 26 * @function main 27 */ 28 int main( int, char** argv ) 29 { 30 /// Load source image 31 src = imread(argv[1]); 32 if (src.empty()) 33 { 34 cerr << "No image supplied ..." << endl; 35 return -1; 36 } 37 38 /// Convert image to gray and blur it 39 cvtColor( src, src_gray, COLOR_BGR2GRAY ); 40 blur( src_gray, src_gray, Size(3,3) ); 41 42 /// Create Window 43 const char* source_window = "Source"; 44 namedWindow( source_window, WINDOW_AUTOSIZE ); 45 imshow( source_window, src ); 46 47 createTrackbar( " Canny thresh:", "Source", &thresh, max_thresh, thresh_callback ); 48 thresh_callback( 0, 0 ); 49 50 waitKey(0); 51 return(0); 52 } 53 54 /** 55 * @function thresh_callback 56 */ 57 void thresh_callback(int, void* ) 58 { 59 Mat canny_output; 60 vector<vector<Point> > contours; 61 vector<Vec4i> hierarchy; 62 63 /// Detect edges using canny 64 Canny( src_gray, canny_output, thresh, thresh*2, 3 ); 65 /// Find contours 66 findContours( canny_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) ); 67 68 /// Draw contours 69 Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 ); 70 for( size_t i = 0; i< contours.size(); i++ ) 71 { 72 Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) ); 73 drawContours( drawing, contours, (int)i, color, 2, 8, hierarchy, 0, Point() ); 74 } 75 76 /// Show in a window 77 namedWindow( "Contours", WINDOW_AUTOSIZE ); 78 imshow( "Contours", drawing ); 79 } 80
