CaptchaRecogition.ImageProcess.Binary C# (CSharp) Метод

        public static Bitmap Binary(Bitmap img)
        {
            int width = img.Width;
            int height = img.Height;
            BitmapData bdata = img.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadWrite,
                PixelFormat.Format32bppRgb);
            unsafe
            {
                byte* start = (byte*)bdata.Scan0.ToPointer();
                for (int i = 0; i < height; i++)
                {
                    for (int j = 0; j < width; j++)
                    {
                        if (start[0] != 255)
                        {
                            start[0] = start[1] = start[2] = 0;
                        }
                        start += 4;
                    }
                    start += bdata.Stride - width * 4;
                }
            }
            img.UnlockBits(bdata);
            return img;
        }

        /// <summary>
        /// 二值化处理
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btn_binary_Click(object sender, EventArgs e)
        {
            //去噪处理后的图片
            Image imgBinary = (Image)pb_noise.Image.Clone();

            //int v2 = ccccccmd.ImageHelper.ComputeThresholdValue((Bitmap)imgBinary);
            // int v2 = ImageProcess.ComputeThresholdValue((Bitmap)imgBinary);
            // imgBinary = ImageProcess.PBinary((Bitmap)imgBinary, v2);
            imgBinary   = ImageProcess.Binary((Bitmap)imgBinary);
            imgBinaried = Image2Num((Bitmap)imgBinary);
            WriteToFile(imgBinaried, "experiment\\" + Path.GetFileNameWithoutExtension(imgurl) + "_binaried.txt");
            pb_noise_binary.Image = imgBinary;
        }