example_02-06.cpp

// Example 2-6. Using cv::pyrDown() to create a new image that is half the width and
// height of the input image
#include <opencv2/opencv.hpp>

void help(char **argv)
{
    std::cout << "\n"
              << "2-06: AUsing cv::pyrDown() to create a new image that is half the width and"
              << "      height of the input image\n"
              << argv[0] << " <path/image>\n"
              << "For example:\n"
              << argv[0] << " ../faces.png\n"
              << std::endl;
}

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

    if (argc != 2)
    {
        help(argv);
        return 0;
    }

    cv::Mat img1, img2;

    cv::namedWindow("Example 2-6-in", cv::WINDOW_AUTOSIZE);
    cv::namedWindow("Example 2-6-out", cv::WINDOW_AUTOSIZE);

    img1 = cv::imread(argv[1]);

    cv::imshow("Example 2-6-in", img1);
    cv::pyrDown(img1, img2);

    cv::imshow("Example 2-6-out", img2);
    cv::waitKey(0);

    return 0;
};