OpenCV图像转换和透视变化 [英] OpenCV image transformation and perspective change

问题描述

我试图实现以下效果，这里使用GIMP中的透视工具。

I'm trying to achieve the following effect, shown here using the perspective tool in GIMP.

原始图片（620x466像素）

转换图片

我有一个固定的网络摄像头，并希望插入上述转换矩阵数字，结果

What I have is a fixed webcam and would like to plugin the above transformation matrix figures, resulting in a trapezium shaped undistorted output.

我知道有其他选项可用于解开OpenCV中的图像，但我真的想手动提供转换矩阵数字，而

I am aware that there are other options available to undistort images in OpenCV, but I would really like to provide transformation matrix figures manually, whilst ending up with a trapezium shaped image.

从阅读中我有一个感觉 warpPerspective ， findHomography 或 getPerspectiveTransform 可能是有用的，但不知道如何在C ++中这样做

From reading around I have a feeling warpPerspective, findHomography or getPerspectiveTransform may be useful, but not sure how to go about this in C++

任何有用的建议都将非常感激。

Any helpful advice would be greatly appreciated.

尝试使用以下代码运行，但我只得到一个窗口1像素显示。

Tried running with the following code but I only get a window with 1 pixel showing.

也许我以像素为单位指定了点数，这是否正确？

Maybe the way I have specified points in pixels, is this correct?

    #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;
}

推荐答案

使用变形仿射变换。如果你有四个角点使用变形透视变换。这里是你应该如何使用变形透视变换。选择图像的四个角点。然后选择所需矩形的四个对应点。变形变换将做剩下的。

If you have three corner points use Warp Affine transform. If you have four corner points use Warp Perspective transform. Here is how you should use Warp Perspective transform. Select four corner points of image. Then select four corresponding points of the desired rectangle. Warp transform will do the rest.

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;  
}

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