Bounding box de una imagen en OpenCV 2.1

/********************************
*      David López Fernández    * 
*    Ingeniero en Informática   *
*        i52lofed@uco.es        *
********************************/
#ifdef _CH_
#pragma package <opencv>
#endif
 
#define CV_NO_BACKWARD_COMPATIBILITY
 
#include "cv.h"
#include "highgui.h"
#include <stdio.h>
#include <limits>
 
using namespace cv;
using namespace std;
 
Rect boundingRect ( const vector<cv::Point> & points )
{
	// Points initialization
	Point min ( std::numeric_limits<int>::max(),std::numeric_limits<int>::max() );
	Point max ( std::numeric_limits<int>::min(),std::numeric_limits<int>::min() );
 
	// Getting bounding box coordinates
	for ( unsigned int i=0;i<points.size();i++ ) {
		if ( points[i].x > max.x ) max.x=points[i].x;
		if ( points[i].x < min.x ) min.x=points[i].x;
 
		if ( points[i].y > max.y ) max.y=points[i].y;
		if ( points[i].y < min.y ) min.y=points[i].y;
	}
 
	return Rect ( min.x,min.y,max.x-min.x+1,max.y-min.y+1 );
} 
 
int main(int argc, char** argv)
{
	// Declares a vector of vectors for store the contours
	vector<vector<Point> > v;
 
	Mat originalimage;
	Mat image;
 
	// Loads the original image
	originalimage = imread("original.ppm");
	// Converts original image to an 8UC1 image
	cvtColor(originalimage, image, CV_BGR2GRAY);
 
	// Finds contours
	findContours(image,v,CV_RETR_LIST,CV_CHAIN_APPROX_NONE);
 
	// Finds the contour with the largest area
	int area = 0;
	int idx;
	for(int i=0; i<v.size();i++) {
		if(area < v[i].size()) {
			idx = i; 
                        area = v[i].size();
                }
	}
 
	// Calculates the bounding rect of the largest area contour
	Rect rect = boundingRect(v[idx]);
	Point pt1, pt2;
	pt1.x = rect.x;
	pt1.y = rect.y;
	pt2.x = rect.x + rect.width;
	pt2.y = rect.y + rect.height;
	// Draws the rect in the original image and show it
	rectangle(originalimage, pt1, pt2, CV_RGB(255,0,0), 1);
 
	cvNamedWindow( "Ejemplo", CV_WINDOW_AUTOSIZE );
	imshow("Ejemplo", originalimage );
	cvWaitKey(0);
 
	cvDestroyWindow("Ejemplo" );
 
}