Reading/writing images

After the introduction of this matrix, we are going to start with the basics of the OpenCV code. Firstly, we need to learn how to read and write images:

#include <iostream>
#include <string>
#include <sstream>
using namespace std;

// OpenCV includes
#include "opencv2/core.hpp"
#include "opencv2/highgui.hpp"
using namespace cv;

int main( int argc, const char** argv )
{
  // Read images
  Mat color= imread("../lena.jpg");
  Mat gray= imread("../lena.jpg", 0);
  
  // Write images
  imwrite("lenaGray.jpg", gray);
  
  // Get same pixel with opencv function
  int myRow=color.cols-1;
  int myCol=color.rows-1;
  Vec3b pixel= color.at<Vec3b>(myRow, myCol);
  cout << "Pixel value (B,G,R): (" << (int)pixel[0] << "," << (int)pixel[1] << "," << (int)pixel[2] << ")" << endl;
  
  // show images
  imshow("Lena BGR", color);
  imshow("Lena Gray", gray);
  // wait for any key press
  waitKey(0);
  return 0;...