C++/OpenCV Bicubic resize of an RGB image - c++

Question

I want to resize an RGB image with the Bicubic interpolation. I used the following code :
// Include standard headers
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <vector>
#include <ctime>
#include <iostream>
using namespace std;
//#include <opencv.hpp>
#include <opencv/cv.h>
#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv/highgui.h>
using namespace cv;
int main()
{
string fileName = "myImage.jpg";
Mat imageSrc = cv::imread(fileName, CV_LOAD_IMAGE_UNCHANGED); // Read the file
if (!imageSrc.data) // Check for invalid input
{
cout << "Could not open or find the image\n";
return 1;
}
cout << "Loaded " << fileName << " (" << imageSrc.channels() << " channels)\n";
imageSrc.convertTo(imageSrc, CV_32F, 1 / 255.0, 0.0);
int SliceSizeWidth = imageSrc.cols / 2;
int sliceShiftWidth = imageSrc.cols / 4;
int sliceWidthNumber = (imageSrc.cols / sliceShiftWidth) - 1;
int SliceSizeHeight = imageSrc.rows / 2;
int sliceShiftHeight = imageSrc.rows / 4;
int sliceHeightNumber = (imageSrc.rows / sliceShiftHeight) - 1;
for (int sliceIndexHeight = 0; sliceIndexHeight < sliceHeightNumber; sliceIndexHeight++)
{
for (int sliceIndexWidth = 0; sliceIndexWidth < sliceWidthNumber; sliceIndexWidth++)
{
Mat patchImage = imageSrc(Rect(sliceIndexWidth*sliceShiftWidth, sliceIndexHeight*sliceShiftHeight, SliceSizeWidth, SliceSizeHeight));
Mat patchImageCopy;
patchImage.copyTo(patchImageCopy); // Deep copy => data are contiguous in patchImageCopy
Mat imageBicubic;
resize(patchImageCopy, imageBicubic, Size(2 * patchImage.cols, 2 * patchImage.rows), INTER_CUBIC);
}
}
return 0;
}
My problem is that even if imageBicubic.channels() = 3, when I want to access the second and the third channels, I can't.
I used this line : cout << imageBicubic.at<float>(25,25,1) << endl; in order to see if the second channel was filled, and it seems that it was not (the dims of my image are 756*1200*3). The .exe just stop working. Without the cout, the .exe works fine.
Do I have something to add on the resize fonction to get a 3D Mat at the end ?
Thank you for your time !