OpenCV图像转换和透视变化

Question

我正在尝试使用GIMP中的透视工具来实现以下效果.

原始图像(620x466像素)

改变形象

我所拥有的是一个固定的网络摄像头,并希望插入上面的变换矩阵图形,从而产生梯形形状的无失真输出.

我知道在OpenCV中还有其他可用于未失真图像的选项,但我真的想手动提供变换矩阵图形,同时最终得到梯形图像.

从阅读中我有一种感觉warpPerspective,findHomography或者getPerspectiveTransform可能有用,但不知道如何在C++中实现这一点

任何有用的建议将不胜感激.

---

尝试使用以下代码运行,但我只得到一个显示1个像素的窗口.

也许我指定像素点的方式,这是正确的吗？

    #include <opencv2/core/core.hpp>
    #include <opencv2/opencv.hpp>
    #include <cv.h>
    #include <opencv2/highgui/highgui.hpp>
    #include <iostream>

    using namespace cv;
    using namespace std;

            cv::Mat OpenWarpPerspective(const cv::Mat& _image
              , const cv::Point2f& _lu
              , const cv::Point2f& _ru
              , const cv::Point2f& _rd
              , const cv::Point2f& _ld
              , const cv::Point2f& _lu_result
              , const cv::Point2f& _ru_result
              , const cv::Point2f& _rd_result
              , const cv::Point2f& _ld_result
              , cv::Mat& _transform_matrix)
            {
              // todo do some checks on input.

              cv::Point2f source_points[4];
              cv::Point2f dest_points[4];


              source_points[0] = _lu;
              source_points[1] = _ru;
              source_points[2] = _rd;
              source_points[3] = _ld;

              dest_points[0] = _lu_result;
              dest_points[1] = _ru_result;
              dest_points[2] = _rd_result;
              dest_points[3] = _ld_result;

              cv::Mat dst;
              _transform_matrix = cv::getPerspectiveTransform(source_points, dest_points);
              cv::warpPerspective(_image, dst, _transform_matrix, dst.size());

              return dst;  
            }

    int main( int argc, char** argv )
    {

        Mat image;
        Mat edited;

        image = imread("c:/org.png", CV_LOAD_IMAGE_COLOR);   // Read the file

        namedWindow( "Display window", CV_WINDOW_AUTOSIZE );// Create a window for display.

            Point2f one = (0.0, 0.0);
            Point2f two = (317.0, 0.0);
            Point2f three = (317.0, 240.0);
            Point2f four = (0.0, 240.0);

            Point2f five = (-100.0, 0.0);
            Point2f six = (617.0, 0.0);
            Point2f seven = (317.0, 240.0);
            Point2f eight = (0.0, 240.0);

            OpenWarpPerspective(image,one,two,three,four,five,six,seven,eight,edited);  

        imshow( "Display window", edited );                   // Show our image inside it.

        waitKey(0);                                          // Wait for a keystroke in the window
        return 0;
}

Answer 1

如果你有三个角点使用Warp仿射变换.如果您有四个角点,请使用Warp Perspective变换.以下是使用Warp Perspective变换的方法.选择图像的四个角点.然后选择所需矩形的四个对应点.Warp变换将完成其余的工作.

cv::Mat OpenWarpPerspective(const cv::Mat& _image
  , const cv::Point2f& _lu
  , const cv::Point2f& _ru
  , const cv::Point2f& _rd
  , const cv::Point2f& _ld
  , const cv::Point2f& _lu_result
  , const cv::Point2f& _ru_result
  , const cv::Point2f& _rd_result
  , const cv::Point2f& _ld_result
  , cv::Mat& _transform_matrix)
{
  // todo do some checks on input.

  cv::Point2f source_points[4];
  cv::Point2f dest_points[4];


  source_points[0] = _lu;
  source_points[1] = _ru;
  source_points[2] = _rd;
  source_points[3] = _ld;

  dest_points[0] = _lu_result;
  dest_points[1] = _ru_result;
  dest_points[2] = _rd_result;
  dest_points[3] = _ld_result;

  cv::Mat dst;
  _transform_matrix = cv::getPerspectiveTransform(source_points, dest_points);
  cv::warpPerspective(_image, dst, _transform_matrix, cv::Size(_width, _height));

  return dst;  
}