OpenCV代码：画出轮廓的外接矩形，和中心点

#include <opencv2/highgui/highgui.hpp>  
#include <opencv2/imgproc/imgproc.hpp>  
#include <iostream>  
#include <stdio.h>  
using namespace std;
using namespace cv;

void find_centrepoint(Mat image, Point &centrepoint, RotatedRect &max_Rect)
{
    
    Mat element = getStructuringElement(MORPH_ELLIPSE, Size(9, 9));
    morphologyEx(image, image, MORPH_OPEN, element);
    morphologyEx(image, image, MORPH_CLOSE, element);
    Mat cannyImage;
    Canny(image, cannyImage, 125, 250, 3);
    vector<vector<Point>> contours;
    vector<Vec4i> hierarchy;
    findContours(cannyImage, contours, hierarchy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);

    //vector<vector<Point> > contours_poly(contours.size());
    vector<RotatedRect> boundRect(contours.size());
    
    for (size_t i = 0; i < contours.size(); i++)
    {
        //approxPolyDP(Mat(contours[i]), contours_poly[i], 3, true);
        boundRect[i] = minAreaRect(Mat(contours[i]));
    }

    vector<Point> max_contour;
    int area = 0;
    int idx;
    for (size_t i = 0; i < contours.size(); i++)
    {
        
        int t_area = boundRect[i].size.area();
        if (t_area>area)
        {
            max_contour = contours[i];
            max_Rect = boundRect[i];
            area = t_area;
            idx = i;
        }
    }
    centrepoint.x = max_Rect.center.x;
    centrepoint.y = max_Rect.center.y;
    Point2f P[4];
    max_Rect.points(P);
    for (int j = 0; j <= 3; j++)
    {
        line(image, P[j], P[(j + 1) % 4], Scalar(255), 2);
    }
    //rectangle(image, max_Rect.tl(), max_Rect.br(), Scalar(255), 4);
    //drawContours(image, contours, idx, Scalar(255), 2, 8);
}
int main(int args, char** argv)
{
    Mat srcImage = imread("D:\Documents\BasedCam2 Files\Picture\贴膜机\镜头2\2018-03-07_15-47-48_030.bmp");
    if (!srcImage.data)
    {
        cout << "读取图像失败" << endl;
        return -1;
    }
    cvtColor(srcImage, srcImage, CV_BGR2GRAY);
    namedWindow("原图像", 0);
    resizeWindow("原图像", srcImage.cols / 4, srcImage.rows / 4);
    imshow("原图像", srcImage);

    Mat T = Mat(srcImage.size(), srcImage.type());
    adaptiveThreshold(srcImage, T, 255, ADAPTIVE_THRESH_MEAN_C, CV_THRESH_BINARY_INV, 25, 5);

    Point centrePoint1;
    RotatedRect max_Rect1;
    find_centrepoint(T, centrePoint1, max_Rect1);

    Mat medImage;
    medianBlur(srcImage, medImage, 9);
    Mat binaryImage;
    threshold(medImage, binaryImage, 128, 255, THRESH_BINARY);
    Point centrePoint2;
    RotatedRect max_Rect2;
    find_centrepoint(binaryImage, centrePoint2, max_Rect2);

    namedWindow("圆外接矩形", 0);
    resizeWindow("圆外接矩形", srcImage.cols / 4, srcImage.rows / 4);
    imshow("圆外接矩形", T);
    namedWindow("膜接矩形", 0);
    resizeWindow("膜接矩形", srcImage.cols / 4, srcImage.rows / 4);
    imshow("膜接矩形", binaryImage);

    waitKey(0);
    return 0;

}
//Mat midImage, dstImage;
    //double fScale = 0.5;
    //Size dsize = Size(srcImage.cols*fScale, srcImage.rows*fScale);
    //resize(srcImage, srcImage,dsize);
    ////imshow("【原始图】", srcImage);

    //cvtColor(srcImage, midImage, CV_BGR2GRAY);//转化边缘检测后的图为灰度图  
    ////medianBlur(midImage, midImage, 9);
    ////bilateralFilter(midImage, midImage, 5, 10,10);
    //imshow("【原始图】", midImage);
    //vector<Vec3f> circles;
    //HoughCircles(midImage, circles, CV_HOUGH_GRADIENT, 1, 50, 100, 50, 200, 0);
    ////依次在图中绘制出圆  
    //for (size_t i = 0; i < circles.size(); i++)
    //{
    //    Point center(cvRound(circles[i][0]), cvRound(circles[i][1]));
    //    int radius = cvRound(circles[i][2]);
    //    //绘制圆心  
    //    circle(srcImage, center, 3, Scalar(0, 255, 0), -1, 8, 0);
    //    //绘制圆轮廓  
    //    circle(srcImage, center, radius, Scalar(155, 50, 255), 3, 8, 0);
    //}

//for (size_t i = 0; i< contours.size(); i++)
//{
//    //        drawContours(drawing, contours_poly, (int)i, color, 1, 8, vector<Vec4i>(), 0, Point());
//    rectangle(T, boundRect[i].tl(), boundRect[i].br(), Scalar(255), 4, 8, 0);
//    //        circle(drawing, center[i], (int)radius[i], color, 2, 8, 0);
//    printf("%d - (%d,%d),(%d,%d)
", i, boundRect[i].x, boundRect[i].y, boundRect[i].width, boundRect[i].height);
//}
//for (size_t i = 0; i < contours.size(); i++)
//{
//    drawContours(T, contours, i, Scalar(255), 1, 8);
//}


//for (int i = 0; i < srcImage.rows; ++i)
//    {
//        for (int j = 0; j < srcImage.cols; ++j)
//        {
//            if (srcImage.at<uchar>(i, j) <= meanImage.at<uchar>(i, j) - 5)
//            {
//                T.at<uchar>(i, j) = 255;
//            }
//            else
//            {
//                T.at<uchar>(i, j) = 0;
//            }
//        }
//    }