【OpenCV】透视变换矫正

演示结果参考：

功能实现：运行程序，会显示图片的尺寸，按回车键后，依次点击需矫正的图片的左上、右上、左下、右下角，结果弹出矫正后的图片，如图上的PIC2对话框。按下字符‘q‘后退出。

代码如下：（注：图中的11.jpg图片自己选取放到该程序目录下。）

#include <opencv2/opencv.hpp>
#include <iostream>
#include <vector>
using namespace std;
using namespace cv;
const int N = 400;
const int M = 220;
Mat img;
Point p1[5];
int flag = 1;
int cnt = 0;
static void mouse_callback(int event, int x, int y, int, void *) {
    //当鼠标左键按下时，记录其坐标
    if(event == EVENT_LBUTTONDOWN) {
        p1[cnt].x = x*1.0; p1[cnt].y = y*1.0;
        cout << "p1 is recorded at " << p1[cnt++] << endl;
    }

    if(cnt==4) {
            cnt=0;
            //变换前图像四个点
            vector<Point2f>src(4);
            src[0] = p1[0];
            src[1] = p1[1];
            src[2] = p1[2];
            src[3] = p1[3];
            //变换后
            vector<Point2f>dst(4);
            dst[0] = Point2f(0, 0);//左上
            dst[1] = Point2f(N, 0);//右上
            dst[2] = Point2f(0, M);//左下
            dst[3] = Point2f(N, M);//右下
            //获取透视变换矩阵

            Mat m = getPerspectiveTransform(src, dst);
            Mat res;

            warpPerspective(img, res, m, Size(N, M),INTER_LINEAR);//实现图像透视变换
            namedWindow("PIC2",1);
            imshow("PIC2", res);
            waitKey(0);
        }    

}
int main() {
    img = imread("11.jpg");
    if(!img.data) {cout<<"read image file wrong!"<<endl; getchar(); return 0;}
    cout << "height = " << img.size().height << ",width = " << img.size().width << endl;
    getchar();

    namedWindow("PIC");
    imshow("PIC", img);

    setMouseCallback("PIC", mouse_callback);//设置鼠标事件回调函数

    while(char(waitKey(1)) != ‘q‘) {}

    return 0;
}

原文地址：https://www.cnblogs.com/GraceSkyer/p/8585105.html