图像像素的重映射

 

 具体代码如下：

#include <opencv2/opencv.hpp>
#include <iostream>
#include <math.h>

using namespace cv;
Mat src, dst, map_x, map_y;
const char* OUTPUT_TITLE = "remap demo";
int index = 0;                             //输入默认为0
void update_map(void);                     //申明函数 
int main(int argc, char** argv) {        
    src = imread("L:/5.jpg");
    if (!src.data) {
        printf("could not load image...
");
        return -1;
    }
    char input_win[] = "input image";
    namedWindow(input_win, CV_WINDOW_AUTOSIZE);
    namedWindow(OUTPUT_TITLE, CV_WINDOW_AUTOSIZE);
    imshow(input_win, src);

    map_x.create(src.size(), CV_32FC1);       //定义map_x.size大小并为浮点型
    map_y.create(src.size(), CV_32FC1);

    //每500ms循环检查输入更新一次
    int c = 0;
    while (true) {
        c = waitKey(500);
        if ((char)c == 27) {                 //若输入为Esc则退出
            break;
        }
        index = c % 4;                       //对输入数值模4取余运算
        update_map();                       //call  update_map()函数
        remap(src, dst, map_x, map_y, INTER_LINEAR, BORDER_CONSTANT, Scalar(0, 0, 255));
        //remap函数参数：1.输入图像  2.输出图像 34.映射表x,y  5.插值方式  6.默认  7. 颜色
        imshow(OUTPUT_TITLE, dst);
    }

    return 0;
}

void update_map(void) {
    for (int row = 0; row < src.rows; row++) {
        for (int col = 0; col < src.cols; col++) {
            switch (index) {

            case 0:   //将原图像缩小一半，后映射到图像中心
                if (col >(src.cols * 0.25) && col <= (src.cols*0.75) && row >(src.rows*0.25) && row <= (src.rows*0.75)) {
                    map_x.at<float>(row, col) = 2 * (col - (src.cols*0.25));
                    map_y.at<float>(row, col) = 2 * (row - (src.rows*0.25));
                }
                else {  //边缘部分0像素填充
                    map_x.at<float>(row, col) = 0;
                    map_y.at<float>(row, col) = 0;
                }
                break;

            case 1://上下颠倒
                map_x.at<float>(row, col) = (src.cols - col - 1);
                map_y.at<float>(row, col) = row;
                break;

            case 2: //左右镜像
                map_x.at<float>(row, col) = col;
                map_y.at<float>(row, col) = (src.rows - row - 1);
                break;

            case 3://上下左右颠倒
                map_x.at<float>(row, col) = (src.cols - col - 1);
                map_y.at<float>(row, col) = (src.rows - row - 1);
                break;
            }

        }
    }
}

结果：

按下0

 按下1：

按下2:

 按下3：