opencv透视变换

关于透视投影的几何知识，以及求解方法，可以参考

http://media.cs.tsinghua.edu.cn/~ahz/digitalimageprocess/chapter06/chapt06_ahz.htm

http://blog.csdn.net/xiaowei_cqu/article/details/26471527

此外，opencv1那本书183页也有讲

这里，实现一个贴图，主要参考

http://www.cnblogs.com/tiandsp/p/4033071.html

那篇博客用的matlab，这里使用opencv2实现

原图

代码

#include <cv.h>
#include <highgui.h>
#include <iostream>
#include <vector>
#include <fstream>

using namespace std;
using namespace cv;

Mat rawImg, dstImg,boardImg,dstboard,maskboard;
vector<Point2f>srcQuad(4);
vector<Point2f>dstQuad(4);

void on_mouse(int event, int x, int y, int flags, void *ustc)//event鼠标事件代号，x,y鼠标坐标，flags拖拽和键盘操作的代号
{
    Point pt;//坐标点;
    char coordinateName[16];
    static int n=0;

    if (event == CV_EVENT_LBUTTONDOWN)//左键按下，读取坐标，并在图像上该点处划圆
    {
        pt = Point(x, y);
        cout << x << " " << y << endl;
        dstQuad[n] = pt;
        n++;
        circle(boardImg, pt, 2, Scalar(255, 0, 0, 0), CV_FILLED, CV_AA, 0);//划圆
        sprintf(coordinateName, "(%d,%d)", x, y);
        putText(boardImg, coordinateName, pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255), 1, 8);//在窗口上显示坐标
        if (n >= 4)
        {
            //imshow("board", boardImg);
            cvDestroyAllWindows();
        }
    }
}
int main()
{
    rawImg = imread("lena.jpg",0);//图片路径
    boardImg = imread("board.jpg",0);
    dstboard = boardImg.clone();
    cvNamedWindow("board",0);
    setMouseCallback("board",on_mouse,0);
    imshow("board",boardImg);
    waitKey(0);
    imshow("raw", rawImg);
    imshow("board", boardImg);
    int imgHeigth = rawImg.rows;
    int imgWidth = rawImg.cols;
    int dstHeigth = boardImg.rows;
    int dstWidth = boardImg.cols;
    srcQuad[0] = Point2f(0,0);//左上 右上 左下 右下
    srcQuad[1] = Point2f(imgWidth-1, 0);
    srcQuad[2] = Point2f(0, imgHeigth - 1);
    srcQuad[3] = Point2f(imgWidth - 1, imgHeigth - 1);
    /*dstQuad[0] = Point2f(imgWidth*0.05, imgHeigth*0.33);
    dstQuad[1] = Point2f(imgWidth*0.9, imgHeigth*0.25);
    dstQuad[2] = Point2f(imgWidth*0.2, imgHeigth*0.7);
    dstQuad[3] = Point2f(imgWidth*0.8, imgHeigth*0.9);*/
    for (int i = 0; i < 4; i++)
        cout << dstQuad[i] << endl;

    Mat warpMatrix = getPerspectiveTransform(srcQuad, dstQuad);
    cout << warpMatrix << endl;
    warpPerspective(rawImg, dstImg, warpMatrix, Size(dstWidth, dstHeigth));

    threshold(dstImg, maskboard, 0, 1, THRESH_BINARY);
    cout << "begin a test of cout to file." << endl;
    // 保存cout流缓冲区指针
    streambuf* coutBuf = cout.rdbuf();
    ofstream of("out.txt");
    // 获取文件out.txt流缓冲区指针
    streambuf* fileBuf = of.rdbuf();
    // 设置cout流缓冲区指针为out.txt的流缓冲区指针
    cout.rdbuf(fileBuf);
    cout << maskboard << endl;

    of.flush();
    of.close();
    // 恢复cout原来的流缓冲区指针
    cout.rdbuf(coutBuf);
    //imshow("rawboard", dstboard);
    cout << "Write Personal Information over..." << endl;
    for (int i = 0; i < dstHeigth - 1; i++)
        for (int j = 0; j < dstWidth - 1; j++)
            dstImg.at<uchar>(i, j) = dstImg.at<uchar>(i, j)*maskboard.at<uchar>(i, j)
            + dstboard.at<uchar>(i, j)*(1-maskboard.at<uchar>(i, j));
    imshow("result", dstImg);
    waitKey();
    return 0;
}

结果