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();
 vector<Point2f>dstQuad();

 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[];
     static int n=;

     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, , Scalar(, , , ), CV_FILLED, CV_AA, );//划圆
         sprintf(coordinateName, "(%d,%d)", x, y);
         putText(boardImg, coordinateName, pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(, , , ), , );//在窗口上显示坐标
         if (n >= )
         {
             //imshow("board", boardImg);
             cvDestroyAllWindows();
         }
     }
 }
 int main()
 {
     rawImg = imread("lena.jpg",);//图片路径
     boardImg = imread("board.jpg",);
     dstboard = boardImg.clone();
     cvNamedWindow("board",);
     setMouseCallback("board",on_mouse,);
     imshow("board",boardImg);
     waitKey();
     imshow("raw", rawImg);
     imshow("board", boardImg);
     int imgHeigth = rawImg.rows;
     int imgWidth = rawImg.cols;
     int dstHeigth = boardImg.rows;
     int dstWidth = boardImg.cols;
     srcQuad[] = Point2f(,);//左上 右上 左下 右下
     srcQuad[] = Point2f(imgWidth-, );
     srcQuad[] = Point2f(, imgHeigth - );
     srcQuad[] = Point2f(imgWidth - , imgHeigth - );
     /*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 = ; i < ; i++)
         cout << dstQuad[i] << endl;

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

     threshold(dstImg, maskboard, , , 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 = ; i < dstHeigth - ; i++)
         for (int j = ; j < dstWidth - ; j++)
             dstImg.at<uchar>(i, j) = dstImg.at<uchar>(i, j)*maskboard.at<uchar>(i, j)
             + dstboard.at<uchar>(i, j)*(-maskboard.at<uchar>(i, j));
     imshow("result", dstImg);
     waitKey();
     return ;
 }

结果