df/d0d/tutorial_find_contours.html

#include "opencv2/imgcodecs.hpp"

#include "opencv2/highgui/highgui.hpp"

#include "opencv2/imgproc/imgproc.hpp"

#include <iostream>

#include <stdio.h>

#include <stdlib.h>


using namespace cv;

using namespace std;


Mat src; Mat src_gray;

int thresh = 100;

int max_thresh = 255;

RNG rng(12345);


void thresh_callback(int, void* );


int main( int, char** argv )

{

 src = imread(argv[1]);

 if (src.empty())

 {

 cerr << "No image supplied ..." << endl;

 return -1;

 }


 cvtColor( src, src_gray, COLOR_BGR2GRAY );

 blur( src_gray, src_gray, Size(3,3) );


 const char* source_window = "Source";

 namedWindow( source_window, WINDOW_AUTOSIZE );

 imshow( source_window, src );


 createTrackbar( " Canny thresh:", "Source", &thresh, max_thresh, thresh_callback );

 thresh_callback( 0, 0 );


 waitKey(0);

 return(0);

}


void thresh_callback(int, void* )

{

 Mat canny_output;

 vector<vector<Point> > contours;

 vector<Vec4i> hierarchy;


 Canny( src_gray, canny_output, thresh, thresh*2, 3 );

 findContours( canny_output, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );


 Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );

 for( size_t i = 0; i< contours.size(); i++ )

 {

 Scalar color = Scalar( rng.uniform(0, 255), rng.uniform(0,255), rng.uniform(0,255) );

 drawContours( drawing, contours, (int)i, color, 2, 8, hierarchy, 0, Point() );

 }


 namedWindow( "Contours", WINDOW_AUTOSIZE );

 imshow( "Contours", drawing );

}