图像的上采样和下采样

#include <opencv2/opencv.hpp>
#include <iostream>
#include <math.h>
using namespace cv;
using namespace std;

Mat src, dst,dst2;

//膨胀腐蚀的应用:消除噪声
int main()
{
    //原图
    src = imread(".//pic//kate.png", IMREAD_UNCHANGED);
    
    char* INPUT_WIN = "input image";
    namedWindow(INPUT_WIN, CV_WINDOW_AUTOSIZE);
    imshow(INPUT_WIN, src);

    //上采样
    pyrUp(src, dst, Size(src.cols * 2, src.rows * 2)); 
    imshow("sample up", dst);

    //下采样
    Mat s_down;
    pyrDown(src, s_down, Size(src.cols / 2, src.rows / 2));
    imshow("sample down", s_down);

    Mat g1, g2,gray_src;
    cvtColor(src, gray_src, CV_BGR2GRAY);
    GaussianBlur(gray_src, g1, Size(3, 3), 0, 0);
    imshow("g1", g1);
    GaussianBlur(g1, g2, Size(3, 3), 0);
    imshow("g2", g2);
    subtract(g1, g2, dst2, Mat());

    //归一化显示
    normalize(dst2, dst2, 255, 0, NORM_MINMAX);
    imshow("res", dst2);

    waitKey(0);
    return 0;
}