段错误 (核心已转储)

./qr 1.jpg
712
 ./qr 1.jpg
段错误 (核心已转储)
./qr 1.jpg
段错误 (核心已转储)

第一次运行可以正常运行检测，第二次则出现该问题
源代码如下：

#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include 
#include 
#include 
#include 
#include 
 
 
using namespace cv;
using namespace std;
 
 
Mat src; Mat src_gray;
 
 
RNG rng(12345);
//Scalar colorful = CV_RGB(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255));
 
 
Point Center_cal(vector<vector<Point> > contours,int i)//找到所提取轮廓的中心点
   {
          int centerx=0,centery=0,n=contours[i].size();
          //在提取的小正方形的边界上每隔周长个像素提取一个点的坐标，求所提取四个点的平均坐标（即为小正方形的大致中心）
          centerx = (contours[i][n/4].x + contours[i][n*2/4].x + contours[i][3*n/4].x + contours[i][n-1].x)/4;
          centery = (contours[i][n/4].y + contours[i][n*2/4].y + contours[i][3*n/4].y + contours[i][n-1].y)/4;
          Point point1=Point(centerx,centery);
          return point1;
   }
 
 
 
 
 
 
int main( int argc, char** argv[] )
{
 
 
  src = imread( "1.jpg", 1 );
  Mat src_all=src.clone();
 
 
 
 
  cvtColor( src, src_gray, CV_BGR2GRAY );
//  src_gray = Scalar::all(255) - src_gray;
  blur( src_gray, src_gray, Size(3,3) );
  equalizeHist( src_gray, src_gray );
  imshow("滤波后",src_gray);
 
 
  Scalar color = Scalar(1,1,255 );
  Mat threshold_output;
  vector<vector<Point> > contours,contours2;
  vector<Vec4i> hierarchy;
  Mat drawing = Mat::zeros( src.size(), CV_8UC3 );
  Mat drawing2 = Mat::zeros( src.size(), CV_8UC3 );
  threshold( src_gray, threshold_output, 112, 255, THRESH_BINARY );
  //Canny(src_gray,threshold_output,136,196,3);
   //imshow("预处理后：",threshold_output);
 
 
  findContours( threshold_output, contours, hierarchy,  CV_RETR_TREE, CHAIN_APPROX_NONE, Point(0, 0) );
  //CHAIN_APPROX_NONE全体,CV_CHAIN_APPROX_SIMPLE,,,RETR_TREE    RETR_EXTERNAL    RETR_LIST   RETR_CCOMP
 
 
    int c=0,ic=0,k=0,area=0;
//
    //程序的核心筛选
    //程序的核心筛选
    int parentIdx=-1;
    for( int i = 0; i< contours.size(); i++ )
    {
        if (hierarchy[i][2] != -1 && ic==0)
        {
            parentIdx = i; 
            ic++;
        }
        else if (hierarchy[i][2] != -1)
        {
            ic++;
        }
        else if(hierarchy[i][2] == -1)
        {
            ic = 0;
            parentIdx = -1;
        }
 
 
        if ( ic >= 2)
        {
            contours2.push_back(contours[parentIdx]);
            drawContours( drawing, contours, parentIdx,  CV_RGB(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255)) , 1, 8);
            ic = 0;
            parentIdx = -1;
            area = contourArea(contours[i]);//得出一个二维码定位角的面积，以便计算其边长（area_side）（数据覆盖无所谓，三个定位角中任意一个数据都可以）
        }
        //cout<<"i= "<}
 
 
    for(int i=0; i<contours2.size(); i++)
        drawContours( drawing2, contours2, i,  CV_RGB(rng.uniform(100,255),rng.uniform(100,255),rng.uniform(100,255)) , -1, 4, hierarchy[k][2], 0, Point() );
 
 
    Point point[3];
    for(int i=0; i<contours2.size(); i++)
    {
        point[i] = Center_cal( contours2, i );
    }
	
	area = contourArea(contours2[1]);//为什么这一句和前面一句计算的面积不一样呢
    int area_side = cvRound (sqrt (double(area)));
    for(int i=0; i<contours2.size(); i++)
    {
        line(drawing2,point[i%contours2.size()],point[(i+1)%contours2.size()],color,area_side/2,8);
    }
 
 
    imshow( "提取后", drawing2 );
    printf("%d\n", contours.size());
    //imshow( "Contours", drawing );
 
 
	//接下来要框出这整个二维码
	Mat gray_all,threshold_output_all;
	vector<vector<Point> > contours_all;
    vector<Vec4i> hierarchy_all;
	cvtColor( drawing2, gray_all, CV_BGR2GRAY );
 
 
	threshold( gray_all, threshold_output_all, 45, 255, THRESH_BINARY );
	findContours( threshold_output_all, contours_all, hierarchy_all,  RETR_EXTERNAL, CHAIN_APPROX_NONE, Point(0, 0) );//RETR_EXTERNAL表示只寻找最外层轮廓
 
 
	//求最小包围矩形，斜的也可以哦
	 RotatedRect rectPoint = minAreaRect(contours_all[0]);
	 Point2f fourPoint2f[4]; 
 
 
	 //将rectPoint变量中存储的坐标值放到 fourPoint的数组中  
	 rectPoint.points(fourPoint2f);
 
 
	  for (int i = 0; i < 4; i++)  
        {  
            line(src_all, fourPoint2f[i%4], fourPoint2f[(i + 1)%4]  
                , Scalar(20,21,237), 3);  
        }  
 
 
	 imshow( "二维码", src_all );
 
 
    waitKey(0);
    return(0);
}

原因
1.图片预处理（模糊+直方图均衡化）后，用查找轮廓不易查找出定位角;
2.致使对contourArea(contours2[0])未定义，后面涉及到contourArea(contours2[1])的运算时会涉及数组越界，造成“段错误（核心已转储）。
解决方法：
将图片预处理部分注释掉

 // blur( src_gray, src_gray, Size(3,3) );
  //equalizeHist( src_gray, src_gray );
  //imshow("滤波后",src_gray);