#include <iostream>
#include "opencv2/opencv.hpp"
#include <stdio.h>

using namespace std;
using namespace cv;


int main(){
Mat img=imread("t.jpg",1);
//blur(img,img,Size(3,3));
medianBlur(img, img, 3);
Mat gray;
cvtColor(img,gray,CV_BGR2GRAY);
Canny(gray, gray, 10, 100, 3);
dilate(gray, gray, Mat(), Point(-1,-1),3);

Mat mask;
threshold( gray, mask, 10, 255,THRESH_BINARY_INV );
medianBlur(mask, mask, 15);

vector< vector <Point> > contours; // Vector for storing contour
 vector< Vec4i > hierarchy;
 int largest_contour_index=0;
 int largest_area=0;

 Mat dst(mask.rows,mask.cols,CV_8UC1,Scalar::all(0)); //create destination image
 findContours( mask.clone(), contours, hierarchy,CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE ); // Find the contours in the image
 for( int i = 0; i< contours.size(); i++ ){
    double a=contourArea( contours[i],false);  //  Find the area of contour
    if(a>largest_area){
    largest_area=a;
    largest_contour_index=i;                //Store the index of largest contour
    }
 }

rectangle(img,boundingRect(contours[largest_contour_index]),Scalar(0,255,0),1,8,0);
imshow("src",img);
imshow("gray",gray);
imshow("mask",mask);
imshow("mask",mask);
waitKey();

}