C++ opencv contrast and Brightness

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <thread>
#include <Windows.h>
using namespace cv;
using namespace std;

int main(int argc, char** argv)
{


double alpha; /**< Simple contrast control */
int beta;  /**< Simple brightness control */


  /// Read image given by user
Mat image = imread("D:\\111.jpg", CV_LOAD_IMAGE_COLOR);
Mat new_image = Mat::zeros(image.size(), image.type());

/// Initialize values
std::cout << " Basic Linear Transforms " << std::endl;
std::cout << "-------------------------" << std::endl;
std::cout << "* Enter the alpha value [1.0-3.0]: "; std::cin >> alpha;
std::cout << "* Enter the beta value [0-100]: "; std::cin >> beta;

/// Do the operation new_image(i,j) = alpha*image(i,j) + beta
for (int y = 0; y < image.rows; y++)
{
for (int x = 0; x < image.cols; x++)
{
for (int c = 0; c < 3; c++)
{
new_image.at<Vec3b>(y, x)[c] = saturate_cast<uchar>(alpha*(image.at<Vec3b>(y, x)[c]) + beta);
}
}
}

/// Create Windows
namedWindow("Original Image", 1);
namedWindow("New Image", 1);

/// Show stuff
imshow("Original Image", image);
imshow("New Image", new_image);

/// Wait until user press some key
waitKey(0);
return 0;
}