/// <summary>

        /// 参数不能是一位索引

        /// </summary>

        /// <param name="bmp"></param>

        /// <returns></returns>

        public Bitmap HoughTransform(Bitmap bmp)

        {

            //// create filter

            //Median Medianfilter = new Median();

            //// apply the filter

            //Medianfilter.ApplyInPlace(bmp);

            Bitmap grayImage;

            if (bmp.PixelFormat != PixelFormat.Format16bppGrayScale && bmp.PixelFormat != PixelFormat.Format8bppIndexed)

            {

                Grayscale grayscalefilter = new Grayscale(0.2125, 0.7154, 0.0721);

                grayImage = grayscalefilter.Apply(bmp);

            }

            else

            {

                grayImage = bmp;

            }

            // invert filter

            Invert invertfilter = new Invert();

            // apply the filter

            invertfilter.ApplyInPlace(grayImage);

            //// Edge Detector  filter

            DifferenceEdgeDetector EdgeDetectorfilter = new DifferenceEdgeDetector();

            //// apply the filter

            EdgeDetectorfilter.ApplyInPlace(grayImage);

            //// create filter

            Dilatation dilatationfilter = new Dilatation();

            //// apply the filter

            dilatationfilter.ApplyInPlace(grayImage);

            return grayImage;

        }