#include <iostream>
#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>

using namespace std;

int main()
{
    string path = "test.jpg";
    cv::Mat img = cv::imread(path, cv::IMREAD_COLOR);
    if (img.empty())
    {
        cout << "failed to read image" << endl;
        return -1;
    }

    double alpha = 0.5, beta = 0;   // alpha < 1
    cv::Mat res1;
    img.convertTo(res1, -1, alpha, beta);
    if (res1.empty())
    {
        cout << "failed to convert image" << endl;
        return -1;
    }
    cv::imshow("src", img);
    cv::imshow("alpha < 1", res1);

    alpha = 1.2, beta = 0;   // alpha > 1
    cv::Mat res2;
    img.convertTo(res2, -1, alpha, beta);
    if (res2.empty())
    {
        cout << "failed to convert image" << endl;
        return -1;
    }
    cv::imshow("alpha > 1", res2);
    cv::waitKey(0);

    return 0;
}