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     ![image description](/upfiles/15333406471443162.png)
        1st-------2nd
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        3rd-------4th

         cv::Mat src= cv::imread( "c://03p.jpg",0);
         if (!src.data)
                         return 0;
         vector<Point> not_a_rect_shape;
        not_a_rect_shape.push_back(Point(122,0));
        not_a_rect_shape.push_back(Point(814,0));
        not_a_rect_shape.push_back(Point(22,540));
        not_a_rect_shape.push_back(Point(910,540));
         // For debugging purposes, draw green lines connecting those points
         // and save it on disk
         const Point* point = &not_a_rect_shape[0];
         int n = (int )not_a_rect_shape.size();
        Mat draw = src.clone();
        polylines(draw, &point, &n, 1, true, Scalar(0, 255, 0), 3, CV_AA);
        imwrite( "draw.jpg", draw);
         // Assemble a rotated rectangle out of that info
        RotatedRect box = minAreaRect(cv::Mat(not_a_rect_shape));
        std::cout << "Rotated box set to (" << box.boundingRect().x << "," << box.boundingRect().y << ") " << box.size.width << "x" << box.size.height << std::endl;
         // Does the order of the points matter? I assume they do NOT.
         // But if it does, is there an easy way to identify and order
         // them as topLeft, topRight, bottomRight, bottomLeft?
         //(0,0) (960,0) (0,540) (960,540)
        cv::Point2f src_vertices[4];
        src_vertices[0] = not_a_rect_shape[0];
        src_vertices[1] = not_a_rect_shape[1];
        src_vertices[2] = not_a_rect_shape[2];
        src_vertices[3] = not_a_rect_shape[3];

        Point2f dst_vertices[4];
        dst_vertices[0] = Point(0, 0);
        dst_vertices[1] = Point(960,0);
        dst_vertices[2] = Point(0,540);
        dst_vertices[3] = Point(960,540);
        Mat warpMatrix = getPerspectiveTransform(src_vertices, dst_vertices);
        cv::Mat rotated;
        warpPerspective(src, rotated, warpMatrix, rotated.size(), INTER_LINEAR, BORDER_CONSTANT);
         // Display the image
        cv::namedWindow( "Original Image");
        cv::imshow( "Original Image",src);
        cv::namedWindow( "warp perspective");
        cv::imshow( "warp perspective",rotated);
        imwrite( "03p.jpg",src);
        cv::waitKey();
        return 0;

     ![image description](/upfiles/15333406471443162.png)
        1st-------2nd
          |         |
          |         |
          |         |
        3rd-------4th

         cv::Mat src= cv::imread( "c://03p.jpg",0);
         if (!src.data)
                         return 0;
         vector<Point> not_a_rect_shape;
        not_a_rect_shape.push_back(Point(122,0));
        not_a_rect_shape.push_back(Point(814,0));
        not_a_rect_shape.push_back(Point(22,540));
        not_a_rect_shape.push_back(Point(910,540));
         // For debugging purposes, draw green lines connecting those points
         // and save it on disk
         const Point* point = &not_a_rect_shape[0];
         int n = (int )not_a_rect_shape.size();
        Mat draw = src.clone();
        polylines(draw, &point, &n, 1, true, Scalar(0, 255, 0), 3, CV_AA);
        imwrite( "draw.jpg", draw);
         // Assemble a rotated rectangle out of that info
        RotatedRect box = minAreaRect(cv::Mat(not_a_rect_shape));
        std::cout << "Rotated box set to (" << box.boundingRect().x << "," << box.boundingRect().y << ") " << box.size.width << "x" << box.size.height << std::endl;
         // Does the order of the points matter? I assume they do NOT.
         // But if it does, is there an easy way to identify and order
         // them as topLeft, topRight, bottomRight, bottomLeft?
         //(0,0) (960,0) (0,540) (960,540)
        cv::Point2f src_vertices[4];
        src_vertices[0] = not_a_rect_shape[0];
        src_vertices[1] = not_a_rect_shape[1];
        src_vertices[2] = not_a_rect_shape[2];
        src_vertices[3] = not_a_rect_shape[3];

        Point2f dst_vertices[4];
        dst_vertices[0] = Point(0, 0);
        dst_vertices[1] = Point(960,0);
        dst_vertices[2] = Point(0,540);
        dst_vertices[3] = Point(960,540);
        Mat warpMatrix = getPerspectiveTransform(src_vertices, dst_vertices);
        cv::Mat rotated;
        warpPerspective(src, rotated, warpMatrix, rotated.size(), INTER_LINEAR, BORDER_CONSTANT);
         // Display the image
        cv::namedWindow( "Original Image");
        cv::imshow( "Original Image",src);
        cv::namedWindow( "warp perspective");
        cv::imshow( "warp perspective",rotated);
        imwrite( "03p.jpg",src);
        cv::waitKey();
        return 0;