d7/d1d/tutorial_hull.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], 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( " Threshold:", "Source", &thresh, max_thresh, thresh_callback );

  thresh_callback( 0, 0 );


  waitKey(0);

  return(0);

}


void thresh_callback(int, void* )

{

  Mat src_copy = src.clone();

  Mat threshold_output;

  vector<vector<Point> > contours;

  vector<Vec4i> hierarchy;


  threshold( src_gray, threshold_output, thresh, 255, THRESH_BINARY );


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


  vector<vector<Point> >hull( contours.size() );

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

     {   convexHull( Mat(contours[i]), hull[i], false ); }


  Mat drawing = Mat::zeros( threshold_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, 1, 8, vector<Vec4i>(), 0, Point() );

       drawContours( drawing, hull, (int)i, color, 1, 8, vector<Vec4i>(), 0, Point() );

     }


  namedWindow( "Hull demo", WINDOW_AUTOSIZE );

  imshow( "Hull demo", drawing );

}