OpenCV: kmeans segmentation C++ - c++

Question

I'm writing a program to recognize the numbers on the image.
I do not see an error in the code. You receive a runtime exception. Indicates Mat.
I use Visual Studio 2015 Community and OpenCV 3.1.
Kmeans segmentation code found on stackoverflow.
Exeption:
test_opencv_nuget.exe!cv::Mat::at >(int i0, int i1)Строка 918 C++
mat.inl.hpp file
line:
CV_DbgAssert((unsigned)(i1 * DataType<_Tp>::channels) < (unsigned)(size.p[1] * channels()));
#include "opencv2/opencv.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/core.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main(int argc, char** argv)
{
VideoCapture cap;
if (!cap.open(0))
return 0;
Mat camera_image;
Mat gray_scale_image;
Mat binary_image;
Mat otsu_binary_image;
Mat laplas_circuit_image;
for (;;)
{
cap >> camera_image;
cvtColor(camera_image, gray_scale_image, cv::COLOR_RGB2GRAY);
threshold(gray_scale_image, otsu_binary_image, 0, 255, CV_THRESH_OTSU);
Mat laplas_kernel = (Mat_<float>(3, 3) << 0, 1, 0,
1, -4, 1,
0, 1, 0);
filter2D(otsu_binary_image, laplas_circuit_image, -1, laplas_kernel);
Mat samples(otsu_binary_image.rows * otsu_binary_image.cols, 3, CV_32F);
for (int y = 0; y < otsu_binary_image.rows; y++)
for (int x = 0; x < otsu_binary_image.cols; x++)
for (int z = 0; z < 3; z++)
samples.at<float>(y + x*otsu_binary_image.rows, z) = otsu_binary_image.at<Vec3b>(y, x)[z];
int clusterCount = 5;
Mat labels;
int attempts = 5;
Mat centers;
kmeans(samples, clusterCount, labels, TermCriteria(CV_TERMCRIT_ITER | CV_TERMCRIT_EPS, 10000, 0.0001), attempts, KMEANS_PP_CENTERS, centers);
Mat kmeans_image(otsu_binary_image.size(), otsu_binary_image.type());
for (int y = 0; y < otsu_binary_image.rows; y++)
for (int x = 0; x < otsu_binary_image.cols; x++)
{
int cluster_idx = labels.at<int>(y + x*otsu_binary_image.rows, 0);
kmeans_image.at<Vec3b>(y, x)[0] = centers.at<float>(cluster_idx, 0);
kmeans_image.at<Vec3b>(y, x)[1] = centers.at<float>(cluster_idx, 1);
kmeans_image.at<Vec3b>(y, x)[2] = centers.at<float>(cluster_idx, 2);
}
imshow("original", camera_image);
imshow("gray_scale", gray_scale_image);
imshow("otsu", otsu_binary_image);
imshow("laplas_circuit", laplas_circuit_image);
imshow("clusters", kmeans_image);
char c = cvWaitKey(33);
if (c == 27) break; // press ESC
}
return 0;
}