example source code - Region of interest image capture from video using opencv

Region of interest image capture from video using opencv

p key is pause, for capture of roi image patch
esc key is stop


..

#include < stdio.h>
#include < iostream>

#include < opencv2\opencv.hpp>

#ifdef _DEBUG        
#pragma comment(lib, "opencv_core249d.lib")
#pragma comment(lib, "opencv_highgui249d.lib")
#else
#pragma comment(lib, "opencv_core249.lib")
#pragma comment(lib, "opencv_highgui249.lib")
#endif 

using namespace std;
using namespace cv;

bool selectObject = false;
Rect selection;
Point origin;
Mat image;
bool pause =false;

Rect PatchRect;
Mat PatchImg;

static void onMouse( int event, int x, int y, int, void* )
{
 if( selectObject & pause)
 {
  
  selection.x = MIN(x, origin.x);
  selection.y = MIN(y, origin.y);
  selection.width = std::abs(x - origin.x);
  selection.height = std::abs(y - origin.y);
  selection &= Rect(0, 0, image.cols, image.rows);
 }

 switch( event )
 {
 case CV_EVENT_LBUTTONDOWN:
  origin = Point(x,y);
  selection = Rect(x,y,0,0);
  selectObject = true;
  break;
 case CV_EVENT_LBUTTONUP:
  if(selectObject && pause)
  {
   if(selection.width > 30 && selection.height > 30 )
   {
    PatchRect = selection;
    image( PatchRect ).copyTo( PatchImg );
    imshow("Selected Img", PatchImg );
   }else
    selection = Rect(0,0,0,0);
  }
  selectObject = false;
  pause = false;
  
  break;
 }
}


int main (void)  
{  


 VideoCapture cap(0);
 Mat frame;
 namedWindow( "Demo", 0 );
 setMouseCallback( "Demo", onMouse, 0 );
 printf("P key is pause, ESC key is exit.\n");

 for(;;)
 {
  if(!pause)
   cap >> frame;
  if( frame.empty() )
   break;
  frame.copyTo(image);


  if( pause && selection.width > 0 && selection.height > 0 )
  {
   rectangle(image, Point(selection.x-1, selection.y-1), Point(selection.x+selection.width+1, selection.y+selection.height+1), CV_RGB(255,0,0) );
  }
  
  imshow( "Demo", image );

  char k = waitKey(10);

  if( k == 27 )
   break;
  else if(k == 'p' || k=='P' )
   pause=!pause;
 }

 return 0;  
}  

--