Opencv Mat - Access violation error c++ - c++

Question

I'm implementing an algorithm, I excuse myself for the extreme for looping, haven't found a better way yet.
The problem is that at the second iteration at line 81 it gives a First-chance exception at 0x000000007707320E (ntdll.dll) in Test.exe: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.
void co_hog(Mat image, int offset, int blockSize, int nrBins, int cat) {
Mat img_x;
Mat img_y;
IplImage img = image;
Mat kern_x = (Mat_<char>(1, 3) << -1, 0, 1);
Mat kern_y = (Mat_<char>(3, 1) << -1, 0, 1);
filter2D(image, img_x, image.depth(), kern_x);
filter2D(image, img_y, image.depth(), kern_y);
Size imageSize = image.size();
int nrBlocksY = imageSize.height / blockSize;
int nrBlocksX = imageSize.width / blockSize;
int degreePerBin = 180 / nrBins;
Mat gradients = Mat(image.size(), CV_32FC1);
Mat magnitudes = Mat(image.size(), CV_32FC1);
for(int y = 0; y < image.rows; y++) {
for(int x = 0; x < image.cols; x++) {
float grad_x = (float)img_x.at<uchar>(y, x);
float grad_y = (float)img_y.at<uchar>(y, x);
gradients.at<float>(y, x) = abs(atan2(grad_y, grad_x) * 180 / PI);
magnitudes.at<float>(y, x) = sqrt(pow(grad_x, 2) + pow(grad_y, 2));
}
}
int bin_1, bin_2, bin_3, bin_4;
double theta_1, theta_2, theta_3, theta_4;
Mat H;
stringstream line(stringstream::in | stringstream::out);
line << cat << " ";
int index = 1;
for(int i = 0; i < nrBlocksY; i++) {
for(int j = 0; j < nrBlocksX; j++) {
Mat coOccMat = Mat::zeros(nrBins, nrBins, CV_32FC1);
for(int q = i * blockSize; q < (i * blockSize) + blockSize; q++) {
for(int p = j * blockSize; p < (j * blockSize) + blockSize; p++) {
for(int offy = -offset; offy < offset; offy++) {
for(int offx = -offset; offx < offset; offx++) {
if((q + offy) >= imageSize.height || (p + offx) >= imageSize.width || (q + offy) < 0 || (p + offx) < 0) {
continue;
}
float m_1 = magnitudes.at<float>(q, p);
float m_2 = magnitudes.at<float>(q + offy, p + offx);
float alpha = gradients.at<float>(q, p);
float beta = gradients.at<float>(q + offy, p + offx);
if(fmod(alpha / degreePerBin, 1) > 0.5) {
bin_1 = floor(alpha / degreePerBin);
bin_2 = bin_1 + 1;
} else {
bin_2 = floor(alpha / degreePerBin);
bin_1 = bin_2 - 1;
}
if(fmod(beta / degreePerBin, 1) > 0.5) {
bin_3 = floor(beta / degreePerBin);
bin_4 = bin_3 + 1;
} else {
bin_4 = floor(beta / degreePerBin);
bin_3 = bin_4 - 1;
}
theta_1 = (bin_1 * degreePerBin) + (degreePerBin / 2);
theta_2 = (bin_2 * degreePerBin) + (degreePerBin / 2);
theta_3 = (bin_3 * degreePerBin) + (degreePerBin / 2);
theta_4 = (bin_4 * degreePerBin) + (degreePerBin / 2);
coOccMat.at<float>(bin_1, bin_3) += (m_1 * (1 - (alpha - theta_1) / (theta_2 - theta_1))) + (m_2 * (1 - (beta - theta_3) / (theta_4 - theta_1)));
coOccMat.at<float>(bin_1, bin_4) += (m_1 * (1 - (alpha - theta_1) / (theta_2 - theta_1))) + (m_2 * ((beta - theta_3) / (theta_4 - theta_1)));
coOccMat.at<float>(bin_2, bin_3) += (m_1 * ((alpha - theta_1) / (theta_2 - theta_1))) + (m_2 * (1 - (beta - theta_3) / (theta_4 - theta_1)));
coOccMat.at<float>(bin_2, bin_4) += (m_1 * ((alpha - theta_1) / (theta_2 - theta_1))) + (m_2 * ((beta - theta_3) / (theta_4 - theta_1)));
}
}
}
}
cout << coOccMat << endl;
-> Next statement to be called *passes the first time* H = coOccMat.reshape(0, 1);
normalize(H, H);
cout << H.size() << endl;
for(int i = 0; i < H.cols; ++i) {
for(int j = 0; j < H.rows; ++j) {
if(H.at<float>(j, i) > 0) {
line << index << ":" << H.at<float>(j, i) << " ";
}
index++;
}
}
cout << "Done" << index << endl;
}
}
}

Answer 1

Problem has been fixed, sometimes the value for a bin was set on -1 so it couldn't access it, debugging tools of visual studio couldn't point out where it went wrong.