RotatedRect minAreaRect( InputArray points ); 

void minEnclosingCircle( InputArray points, 
                   CV_OUT Point2f& center, CV_OUT float& radius ); 

#include "core/core.hpp"  
#include "highgui/highgui.hpp"  
#include "imgproc/imgproc.hpp"  
#include "iostream" 
 
using namespace std;  
using namespace cv;  
 
int main(int argc,char *argv[])  
{ 
  Mat imageSource=imread(argv[1],0); 
  imshow("Source Image",imageSource); 
  Mat image; 
  blur(imageSource,image,Size(3,3)); 
  threshold(image,image,0,255,CV_THRESH_OTSU);   
  imshow("Threshold Image",image); 
 
  //尋找最外層輪廓 
  vector<vector<Point>> contours; 
  vector<Vec4i> hierarchy; 
  findContours(image,contours,hierarchy,RETR_EXTERNAL,CHAIN_APPROX_NONE,Point()); 
 
  Mat imageContours=Mat::zeros(image.size(),CV_8UC1); //最小外接矩形畫布 
  Mat imageContours1=Mat::zeros(image.size(),CV_8UC1); //最小外結(jié)圓畫布 
  for(int i=0;i<contours.size();i++) 
  {     
    //繪制輪廓 
    drawContours(imageContours,contours,i,Scalar(255),1,8,hierarchy); 
    drawContours(imageContours1,contours,i,Scalar(255),1,8,hierarchy); 
 
 
    //繪制輪廓的最小外結(jié)矩形 
    RotatedRect rect=minAreaRect(contours[i]); 
    Point2f P[4]; 
    rect.points(P); 
    for(int j=0;j<=3;j++) 
    { 
      line(imageContours,P[j],P[(j+1)%4],Scalar(255),2); 
    } 
 
    //繪制輪廓的最小外結(jié)圓 
    Point2f center; float radius; 
    minEnclosingCircle(contours[i],center,radius); 
    circle(imageContours1,center,radius,Scalar(255),2); 
 
  } 
  imshow("MinAreaRect",imageContours);   
  imshow("MinAreaCircle",imageContours1);  
  waitKey(0); 
  return 0;