c++ dynamic allocation with opencv exception

Question

i have the following code. i used it after applying connected components code i have the wanted results from connected components but i'm trying using the following code to remove the very small or very high labels based on a threshold.but every time i debug it i have exception.. so could anybode help me please this is the connected components code

 #include <stdio.h>
#include <math.h>
#include <cv.h>
#include <highgui.h>
#define PIXEL(img,x,y) (img)->imageData[(x)*img->widthStep+(y)]

#include <iostream>
int main()

{

IplImage *GrayImg,*outImg;

GrayImg=cvLoadImage("Gray_Image.jpg",0);

if(!GrayImg){
printf("Could not load image file: %s\n");
cvWaitKey(0);
exit(0);
}

cvThreshold(GrayImg, GrayImg, 180, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);//converting image to binary 


int height,width,channels;

height = GrayImg->height;
width = GrayImg->width;
channels = GrayImg->nChannels;

printf("Processing a %dx%d image with %d channels \n",height,width,channels); 

outImg = cvCreateImage(cvSize(width, height), IPL_DEPTH_8U, 1);
cvZero(outImg);
//cvCopyImage(GrayImg,OutImg);

int i,j,v;
int top,left;
int topL,leftL;
int label=0;
int eq[10000][2];
int eqlength = 1;

cvNamedWindow("Gray", CV_WINDOW_AUTOSIZE); 
cvShowImage("Gray", GrayImg );



for (i=0;i<height;i++) {
    for (j=0;j<width;j++) {
        v = (unsigned char) PIXEL(GrayImg,i,j);// cvGet2D(GrayImg,i,j).val[0];
        //unsigned char v1 = PIXEL(GrayImg,i,j);
        //int v2 = PIXEL(GrayImg,i,j);
        //int v3 = v1;
        if (v==255) {
            if (i>0) top = cvGet2D(GrayImg,i-1,j).val[0];
                else top = 0;
            if (j>0) left = cvGet2D(GrayImg,i,j-1).val[0] ;
                else left=0;

            if (top==0 && left==0) 
            {
                PIXEL(outImg,i,j) = label;
                label+=1;
            }
            else if (top==255 && left==0) {
                PIXEL(outImg,i,j) = PIXEL(outImg,i-1,j);
            }
            else if (top==0 && left==255) {
                PIXEL(outImg,i,j) = PIXEL(outImg,i,j-1);
            }
            else if (top==255 && left==255) {
                PIXEL(outImg,i,j) = PIXEL(outImg,i,j-1);
                if (PIXEL(outImg,i-1,j) != PIXEL(outImg,i,j-1)){
                    if (eq[eqlength-1][0] == PIXEL(outImg,i-1,j) && eq[eqlength-1][1] == PIXEL(outImg,i,j-1)) ;
                    else
                    {
                        eq[eqlength][0] = PIXEL(outImg,i-1,j);
                        eq[eqlength][1] = PIXEL(outImg,i,j-1);
                        eqlength++;
                    }
                }
            }


        }
    }




    //cvWaitKey(0);
            //cvShowImage("Out", outImg);
}

int e;

        for (i=0;i<height;i++) 
            for (j=0;j<width;j++)
                if (PIXEL(outImg,i,j)!=0) 
                    for (e=1;e<eqlength;e++) 
                        if (PIXEL(outImg,i,j)==eq[e][0])
                            PIXEL(outImg,i,j)=eq[e][1];


cvNamedWindow("Out", CV_WINDOW_AUTOSIZE); 
cvShowImage("Out", outImg);

and this is the code i added to remove unwanted labels

    int* arr  = new int [N];


//cout<<endl<<arr[0];
for (i=0;i<height;i++) 
    {
        for (j=0;j<width;j++)
            {
                id=(unsigned char)PIXEL(outImg,i,j);
                arr[id]++;
            }
    }

    for (i=0;i<=N;i++)
    {
        if (arr[i]<5 || arr[i]>50)
          arr[i]=0;
    }

    for (i=0;i<outImg->height;i++) 
    {
        for (j=0;j<outImg->width;j++)
            {
                id=(unsigned char)PIXEL(outImg,i,j);
                //id=cvGet2D(outImg,i,j).val[0];
                if (arr[id]==0)
                PIXEL(outImg,i,j)=0;
                else
                PIXEL(outImg,i,j)=255;


            }
    }



    delete [] arr;



cvNamedWindow("CC", CV_WINDOW_AUTOSIZE); 
cvShowImage("CC", outImg);

cvWaitKey(0);



/* Free memory and get out */


cvDestroyWindow("Gray");

cvReleaseImage(&GrayImg);


return 0;

}

Answer 1

You are exceeding the bounds of your array arr. Indexes are 0 based in C++ so when allocating an array of size N your maximum index is N-1.

int* arr  = new int [N];
...
for (i=0;i<=N;i++) // Accessing element N of arr which does not exist. Use '<'
{
    if (arr[i]<5 || arr[i]>50)
      arr[i]=0;
}