Image processing error - c++

Question

I must implement in C++ using diblok The Seeded Region Growing algorithm due to Adams and Bischof which can be found here http://bit.ly/1nIxphj.
It is the fig.2 pseudocode.
After I choose the seeded points using the mouse , it throws this message : Unhandled exception at 0x00416ca0 in diblook.exe: 0xC0000005: Access violation reading location 0x3d2f6e68.
This is the code of the function:
void CDibView::OnLButtonDblClk(UINT nFlags, CPoint point)
{ BEGIN_SOURCE_PROCESSING;
int** labels = new int* [dwHeight];
for(int k = 0;k < dwHeight; k++)
labels[k] = new int[dwWidth];
int noOfRegions = 2;
double meanRegion[2];
double noOfPointsInRegion[2];
for(int i = 0; i < dwHeight ; i++)
for(int j = 0; j < dwWidth ; j++)
{
labels[i][j] = -1;
}
if(noOfPoints < 6)
{
CPoint p = GetScrollPosition() + point;
pos[noOfPoints].x = p.x;
pos[noOfPoints].y = p.y;
int regionLabel = 0;
if(noOfPoints <= noOfPoints / 2)
labels[p.x][p.y] = regionLabel;
else
labels[p.x][p.y] = regionLabel + 1;
noOfPoints++;
}
else
{
// Calculate the mean of each region
for(int i = 0; i < noOfRegions; i++)
{
for(int j = 0 ; j < noOfPoints; j++)
{
if(labels[pos[j].x][pos[j].y] == i)
{
meanRegion[i] += lpSrc[pos[j].x * w + pos[j].y];
}
}
meanRegion[i] /= 3;
noOfPointsInRegion[i] = 3;
}
for(int seedPoint = 0; seedPoint < noOfPoints; seedPoint++)
{
// define list
node *start, *temp;
start = (node *) malloc (sizeof(node));
temp = start;
temp -> next = NULL;
for(int i = -1; i <= 1; i++)
for(int j = -1; j<= 1; j++)
{
if(i == 0 && j == 0) continue;
int gamma = lpSrc[(pos[seedPoint].x + i) * + pos[seedPoint].y + j] - lpSrc[pos[seedPoint].x * w + pos[seedPoint].y];
push(start, pos[seedPoint].x + i, pos[seedPoint].y + j, gamma);
}
sort(start);
if(start != NULL)
{
node *y = start;
pop(start);
int sameNeighbour = 1;
int neighValue = -1;
for(int k = -1; k <= 1; k++)
for(int l = -1; l <= 1;l++)
{
if(k ==0 && l==0) continue;
if(labels[y -> x + k][y -> y + l] != -1)
{
neighValue = labels[y -> x + k][y -> y + l];
break;
}
}
for(int k = -1; k <= 1; k++)
for(int l = -1; l <= 1;l++)
{
if(k == 0 && l==0) continue;
if(labels[y -> x + k][y -> y = 1] != -1 && labels[y -> x + k][y -> y + l] != neighValue)
sameNeighbour = 0;
}
if(sameNeighbour == 1)
{
labels[y -> x][y -> y] = neighValue;
meanRegion[neighValue] = meanRegion[neighValue] * noOfPointsInRegion[neighValue] / noOfPointsInRegion[neighValue] + 1;
noOfPointsInRegion[neighValue]++;
for(int k = -1; k <= 1; k++)
for(int l = -1; l <= 1;l++)
{
if(k == 0 && l == 0) continue;
if(labels[y -> x + k][y -> y + l] == -1 && find(start, y->x + k, y->y + l) == 0)
{
int gammak = meanRegion[neighValue] - lpSrc[(y->x +k) * w + (y->y + l)];
push(start, y->x + k, y->y + l, gammak);
sort(start);
}
}
}
else
{
labels[y->x][y->y] = -1;
}
}
}
int noOfRegionOne = 0;
int noOfRegionTwo = 0;
int noOfBoundary = 0;
for(int i = 0; i< dwHeight; i++)
for(int j = 0;j<dwWidth; j++)
{
if(labels[i][j] == -1)
noOfBoundary++;
else if(labels[i][j] == 0)
noOfRegionOne++;
else if(labels[i][j] == 1)
noOfRegionTwo++;
}
CString info;
info.Format("Boundary %d, One %d, Two %d", noOfBoundary, noOfRegionOne, noOfRegionTwo);
AfxMessageBox(info);
noOfPoints = 0;
}
CScrollView::OnLButtonDblClk(nFlags, point);
END_SOURCE_PROCESSING;
}
After a choose to break the running, this is what is shown http://postimg.org/image/j2sh9k0a1/
Can anybody tell what is wrong and why it doesn't work?
Thanks.

Answer 1

Your screenshot shows that your node (Y is a terrible name, incidentally) has garbage values in it. Offhand, I suspect that 'sort' is overwriting your node values, resulting in garbage. I would create a static copy of your current node to prevent it from changing during processing:
Change
node *y = start;
pop(start);
to
node y = *start;
pop(start);