Problems writing to a subsection of a Mat-Object - c++

Question

I'm new to OpenCV a have some trouble regarding writing to a subrange of a Mat-Object.
The code below iterates a given Image. For each pixel, it takes pixel within a range of 5x5, finds the brightest pixel, and put all other pixel to 0.
I call the function multiple times. After a random number of calls the function gives me a segmentation fault or "malloc memory corruption". Sometimes I can call the function 10 times with no problems sometimes only twice, then the program stops.
I tracked down the problem to the line, where I write to the original image using the subimage.
subimage.at<uchar>(rowSubimage,colSubimage) = 0;
There is the function that drives me crazy:
void findMaxAndBlackout(Mat& image, int size){
Point centralPoint;
Size rangeSize = Size(size,size);
Mat subimage;
Rect range;
// iterate the image
for(int row = 0; row <= image.rows-size; row++){
for(int col = 0; col <= image.cols-size; col++){
centralPoint = Point(col,row);
range = Rect(centralPoint, rangeSize);
// slice submatrix and find max
subimage = image(range);
double max;
minMaxLoc( subimage, NULL, &max, NULL, NULL );
// iterate the surrounding
for(int rowSubimage = 0; rowSubimage <= subimage.rows; rowSubimage++){
for(int colSubimage = 0; colSubimage <= subimage.cols; colSubimage++){
if(subimage.at<uchar>(rowSubimage,colSubimage) < max){
//this line cause the trouble
subimage.at<uchar>(rowSubimage,colSubimage) = 0;
}
}
}
}
}}
The Mat-Object is generated using:
Mat houghImage = imread("small_schachbrett1_cam.png", CV_LOAD_IMAGE_GRAYSCALE);
Please help me understand the problem.
If you know a better or more efficient way to achieve the same result please let me know. I am open for any improvements
Regards
benniz

Answer 1

You are out of range:
row <= image.rows-size
col <= image.cols-size
rowSubimage <= subimage.rows
colSubimage <= subimage.cols
should be
row < image.rows-size
col < image.cols-size
rowSubimage < subimage.rows
colSubimage < subimage.cols