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/**
* @function generalContours_demo2.cpp
* @brief Demo code to obtain ellipses and rotated rectangles that contain detected contours
* @author OpenCV team
*/
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;
Mat src_gray;
int thresh = 100;
RNG rng(12345);
/// Function header
void thresh_callback(int, void* );
/**
* @function main
*/
int main( int argc, char** argv )
{
/// Load source image and convert it to gray
CommandLineParser parser( argc, argv, "{@input | ../data/stuff.jpg | input image}" );
Mat src = imread( parser.get<String>( "@input" ) );
if( src.empty() )
{
cout << "Could not open or find the image!\n" << endl;
cout << "Usage: " << argv[0] << " <Input image>" << endl;
return -1;
}
/// Convert image to gray and blur it
cvtColor( src, src_gray, COLOR_BGR2GRAY );
blur( src_gray, src_gray, Size(3,3) );
/// Create Window
const char* source_window = "Source";
namedWindow( source_window );
imshow( source_window, src );
const int max_thresh = 255;
createTrackbar( "Canny thresh:", source_window, &thresh, max_thresh, thresh_callback );
thresh_callback( 0, 0 );
waitKey();
return 0;
}
/**
* @function thresh_callback
*/
void thresh_callback(int, void* )
{
/// Detect edges using Canny
Mat canny_output;
Canny( src_gray, canny_output, thresh, thresh*2 );
/// Find contours
vector<vector<Point> > contours;
findContours( canny_output, contours, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );
/// Find the rotated rectangles and ellipses for each contour
vector<RotatedRect> minRect( contours.size() );
vector<RotatedRect> minEllipse( contours.size() );
for( size_t i = 0; i < contours.size(); i++ )
{
minRect[i] = minAreaRect( contours[i] );
if( contours[i].size() > 5 )
{
minEllipse[i] = fitEllipse( contours[i] );
}
}
/// Draw contours + rotated rects + ellipses
Mat drawing = Mat::zeros( canny_output.size(), CV_8UC3 );
for( size_t i = 0; i< contours.size(); i++ )
{
Scalar color = Scalar( rng.uniform(0, 256), rng.uniform(0,256), rng.uniform(0,256) );
// contour
drawContours( drawing, contours, (int)i, color );
// ellipse
ellipse( drawing, minEllipse[i], color, 2 );
// rotated rectangle
Point2f rect_points[4];
minRect[i].points( rect_points );
for ( int j = 0; j < 4; j++ )
{
line( drawing, rect_points[j], rect_points[(j+1)%4], color );
}
}
/// Show in a window
imshow( "Contours", drawing );
}