can someone supply code to extract an image from pdf file using pdfsharp

PdfDocument document = PdfReader.Open(textBox_fichero.Text);
 PdfSharp.Pdf.PdfObject[] Todosobjetos = document.Internals.GetAllObjects();
 for(int I=0;I<Todosobjetos.Length;I++)
           {
               if(Todosobjetos[I].GetType().Name == typeof(PdfDictionary).Name)
               {
                   PdfDictionary Referencia = Todosobjetos[I] as PdfDictionary;
                   string Tipo = Referencia.Elements.GetString("/Type");
                   if(Tipo== "/XObject")
                   {
                       if(Referencia.Elements.GetString("/Subtype")=="/Image")
                               {
                                  string extension = "";
                                  ExportImage(Referencia, Nombre, ref extension))
                                  Contador_Imagenes++;
                               }
                   }
               }
           }

pubilc void ExportImage(PdfDictionary image, string  nombre_fichero,ref string extension)
        {
            string filter;
           
            try
            {
                filter = image.Elements.GetName("/Filter");
            }
            catch
            {
                filter = "/DCTDecode";
            }

            try
            {
                switch (filter)
                {
                    case "/DCTDecode":
                        {
                            extension=".jpg";
                            ExportJpegImage(image, nombre_fichero);
                        }
                        break;
                    case "/FlateDecode":
                        {
                            extension = ".png";
                            ExportAsPngImage(image, nombre_fichero);
                        }
                        break;
                }
            }
            catch
            {
                Errores ++ ;           
            }

        }

private void ExportJpegImage(PdfDictionary ImagePdfDictionary, string nombre_fichero)
       {
           // Fortunately JPEG has native support in PDF and exporting an image is just writing the stream to a file.
           byte[] stream = ImagePdfDictionary.Stream.Value;

           if (CheckBox_InvertirColores.Checked)
           {
               using (MagickImage magickImage = new MagickImage(stream))
               {
                   magickImage.Negate();
                   magickImage.Write(nombre_fichero);
               }
           }
           else
           {
               FileStream fs = new FileStream(nombre_fichero, FileMode.Create, FileAccess.Write);
               BinaryWriter bw = new BinaryWriter(fs);
               bw.Write(stream);
               bw.Close();
               bw.Dispose();
               fs.Close();
               fs.Dispose();
           }
       }
       private void ExportAsPngImage(PdfDictionary image, string nombre_fichero)
       {
           int width = image.Elements.GetInteger(PdfImage.Keys.Width);
           int height = image.Elements.GetInteger(PdfImage.Keys.Height);
           var canUnfilter = image.Stream.TryUnfilter();
           byte[] decodedBytes;

           if (canUnfilter)
           {
               decodedBytes = image.Stream.Value;
           }
           else
           {
               PdfSharp.Pdf.Filters.FlateDecode flate = new PdfSharp.Pdf.Filters.FlateDecode();
               decodedBytes = flate.Decode(image.Stream.Value);
           }

           int bitsPerComponent = 0;
           while (decodedBytes.Length - ((width * height) * bitsPerComponent / 8) != 0)
           {
               bitsPerComponent++;
           }

           System.Drawing.Imaging.PixelFormat pixelFormat;
           switch (bitsPerComponent)
           {
               case 1:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format1bppIndexed;
                   break;
               case 8:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format8bppIndexed;
                   break;
               case 16:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format16bppArgb1555;
                   break;
               case 24:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format24bppRgb;
                   break;
               case 32:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format32bppArgb;
                   break;
               case 64:
                   pixelFormat = System.Drawing.Imaging.PixelFormat.Format64bppArgb;
                   break;
               default:
                   throw new Exception("Unknown pixel format " + bitsPerComponent);
           }

           Array.Reverse(decodedBytes);

           Bitmap bmp = new Bitmap(width, height, pixelFormat);
           BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.WriteOnly, bmp.PixelFormat);

           System.Runtime.InteropServices.Marshal.Copy(decodedBytes, 0, bmpData.Scan0, decodedBytes.Length);

           bmp.UnlockBits(bmpData);
           bmp.RotateFlip(RotateFlipType.Rotate180FlipNone);
           bmp.Save(nombre_fichero, System.Drawing.Imaging.ImageFormat.Png);
       }