private void CannyEdgeDetection()
        {
            Image<Gray, Byte> grayImage = new Image<Gray, byte>(imageBox1.Image.Bitmap);
            var blurredImage = grayImage.SmoothGaussian(5, 5, 0, 0);
            var cannyImage = new UMat();
            CvInvoke.Canny(blurredImage, cannyImage, 50, 150);

            Image<Gray, Byte> showCanny = new Image<Gray, byte>(cannyImage.Bitmap);
            imageBox4.Image = showCanny;
        }

        private void CannyOCR()
        {
            //sobel
            Image<Bgr, Byte> img = new Image<Bgr, byte>(imageBox1.Image.Bitmap);
            Image<Gray, byte> sobel = img.Convert<Gray, byte>().Sobel(1, 0, 3).AbsDiff(new Gray(0.0)).Convert<Gray, byte>().ThresholdBinary(new Gray(50), new Gray(255));
            Mat SE = CvInvoke.GetStructuringElement(Emgu.CV.CvEnum.ElementShape.Rectangle, new Size(10, 2), new Point(-1, -1));
            sobel = sobel.MorphologyEx(Emgu.CV.CvEnum.MorphOp.Dilate, SE, new Point(-1, -1), 1, Emgu.CV.CvEnum.BorderType.Reflect, new MCvScalar(255));
            Emgu.CV.Util.VectorOfVectorOfPoint contours = new Emgu.CV.Util.VectorOfVectorOfPoint();
            Mat m = new Mat();

            CvInvoke.FindContours(sobel, contours, m, Emgu.CV.CvEnum.RetrType.External, Emgu.CV.CvEnum.ChainApproxMethod.ChainApproxSimple);

            List<Rectangle> list = new List<Rectangle>();

            for (int i = 0; i < contours.Size; i++)
            {
                Rectangle brect = CvInvoke.BoundingRectangle(contours[i]);

                double ar = brect.Width / brect.Height;
                if (ar > 2 && brect.Width > 25 && brect.Height > 8 && brect.Height < 100)
                {
                    list.Add(brect);
                }
            }