OpenCV利用透视变换将斜体校正

    cv::Mat src = cv::imread("D:\\sxl\\处理图片\\斜体分割\\测试图\\正2.png");
    if (!src.data)
        return;
    //--------------旋转------------------------------------------------------
    double angle = 19;
    Point2f center(src.cols / 2, src.rows / 2);
    Mat rot = getRotationMatrix2D(center, angle, 1);
    Rect bbox = RotatedRect(center, src.size(), angle).boundingRect();

    rot.at<double>(0, 2) += bbox.width / 2.0 - center.x;
    rot.at<double>(1, 2) += bbox.height / 2.0 - center.y;

    //设置选择背景边界颜色：绿色 
    Scalar borderColor = Scalar(255, 255, 255);
    Mat dst;
    warpAffine(src, dst, rot, bbox.size(), INTER_LINEAR, BORDER_CONSTANT, borderColor);

    Mat gray, BinImg;
    if (dst.channels() == 3)
    {
        cvtColor(dst, gray, CV_BGR2GRAY);   //转换成灰度图
    }
    else
    {
        gray = dst;
    }
    //--------------旋转------------------------------------------------------


    vector<Point> not_a_rect_shape;
    not_a_rect_shape.push_back(Point(3, 82));
    not_a_rect_shape.push_back(Point(2, 276));
    not_a_rect_shape.push_back(Point(234, 191));
    not_a_rect_shape.push_back(Point(239, 1));
    // 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 = gray.clone();
    polylines(draw, &point, &n, 1, true, Scalar(0, 255, 0), 3, CV_AA);
    imwrite("draw.jpg", draw);
    //  topLeft, topRight, bottomRight, bottomLeft
    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(2, 2);
    dst_vertices[1] = Point(0, 194);
    dst_vertices[2] = Point(235, 190);
    dst_vertices[3] = Point(239, 1);
    Mat warpMatrix = getPerspectiveTransform(src_vertices, dst_vertices);
    cv::Mat rotated;
    warpPerspective(gray, 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("result.jpg", src);
    cv::waitKey();
    return ;

效果图：