Blurring images of an image pyramid - Vector subscript out of range - c++

Question

I am trying to load an image, calculate the image pyramid (save every image) and then blur every single image of the pyramid with opencv 3.2 in C++. When I run my program I receive the error:
vector Line:1740 Expression: vector subscript out of range
Here is my code:
#include "stdafx.h"
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/xfeatures2d.hpp>
#include <iostream>
#include <opencv2/shape/shape.hpp>
using namespace std;
using namespace cv;
using namespace cv::xfeatures2d;
int main(int argc, char** argv)
{
// Read the image
Mat img_1;
img_1 = imread(argv[1], CV_LOAD_IMAGE_GRAYSCALE);
// Build an image pyramid and save it in a vector of Mat
vector<Mat> img_1_pyramid;
int pyramid_octaves = 3;
buildPyramid(img_1, img_1_pyramid, pyramid_octaves);
/* void cv::buildPyramid (InputArray src, OutputArrayOfArrays dst, int
maxlevel, int borderType = BORDER_DEFAULT) */
// Initialize parameters for the first image pyramid
vector<Mat> reduced_noise_1;
blur(img_1_pyramid[0], reduced_noise_1[0], Size(3,3));
/* void cv::blur (InputArray src, OutputArray dst, Size ksize, Point
anchor=Point(-1,-1), int borderType=BORDER_DEFAULT)*/
return 0;
}
I also tried it with a Mat object: Mat reduced_noise_1; or a vector of predefined size vector<Mat> reduced_noise(4);and I can draw img_1_pyramid[0] with imshow and receive the right image...
When I debug the program I receive an error in Line 621 of cvstd.hpp:
String::String(const char* s)
: cstr_(0), len_(0)
{
if (!s) return;
size_t len = strlen(s); // Here appears the error (only in German;))
memcpy(allocate(len), s, len);
}