如何访问网站外的图片

  private void Show()
        {
            try
            {
                Bitmap bitmap = new Bitmap(@"C:\FTPUPLOAD\LocalUser\YH1\FM\Chrysanthemum.jpg");
                Response.ContentType = "image/jpeg";
                bitmap.Save(Response.OutputStream, ImageFormat.Jpeg);
            }
          catch(Exception ex)
            {
                Response.Write("<script>alert(‘" + ex.Message+ "‘);</script>");
            }