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 */
main(int,char ** argv)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 */
thresh_callback(int,void *)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