Reading/writing images

Following the introduction to matrices, we are going to start with the OpenCV code basics. The first thing that we have to learn is 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",CV_LOAD_IMAGE_GRAYSCALE); 

  if(! color.data ) // Check for invalid input
 {
 cout << "Could not open or find the image" << std::endl ;
 return -1;
 }
   // 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] ...