#include <string>

 #include <iostream>

 #include <stdio.h>

 #include <fstream>

 #include<math.h>

 #include <opencv2\opencv.hpp>

 #include <opencv2\highgui\highgui.hpp>

 #include <opencv2\imgproc\imgproc.hpp>

 #include <opencv2\core\core.hpp>

 using namespace std;

 using namespace cv;

 #define threshold_diff 20

 int main()

 {

     Mat src1 = imread("图片1.png"), gray1;

     cvtColor(src1, gray1, COLOR_BGR2GRAY);

     Mat src2 = imread("图片2.png"), gray2;

     cvtColor(src2, gray2, COLOR_BGR2GRAY);

     //降噪

     blur(gray1, gray1, Size(, ));

     blur(gray2, gray2, Size(, ));

     //二值化

     Mat gray_diff;

     //CvMat *src1, *src2;

     //cvAbsDiff(gray_src_y, gray_src_no, abs_src);

     subtract(gray2, gray1, gray_diff);

     for (int i = ; i < gray_diff.rows; i++)

     {

         for (int j = ; j < gray_diff.cols; j++)

         {

             if (abs(gray_diff.at<unsigned char>(i,j)) >= threshold_diff)

                 gray_diff.at<unsigned char>(i, j) = ;

             else

                 gray_diff.at<unsigned char>(i, j) = ;

         }

     }

     //开运算（膨胀腐蚀算子）

     Mat out;

     Mat element = getStructuringElement(MORPH_RECT, Size(, ));

     erode(gray_diff, out, element);

     dilate(out, out, element);

     //查找轮廓

     Mat dst = Mat::zeros(out.size(), CV_8UC3);

     vector<vector<Point>> contours;

     vector<Vec4i> hierarchy;

     findContours(out, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);

     int index = , largestComp;

     double maxArea = ;

     for (; index >= ; index  = hierarchy[index][])

     {

         const vector<Point>& c = contours[index];

         double area = fabs(contourArea(Mat(c)));

         if (area >maxArea)

         {

             maxArea = area;

             largestComp = index;

         }

     }

     Scalar color(, , );

     drawContours(dst, contours, largestComp, color, CV_FILLED, , hierarchy);

     imshow("轮廓图", dst);

     imshow("原图", src1);

     imshow("放入物品", src2);

     imshow("图片差", gray_diff);

     imshow("开运算", out);

     waitKey();

     system("pause");

     return ;

 }