protected void Page_Load(object sender, EventArgs e)
 {
     if (!Page.IsPostBack)
     {
         string strCaptchaImageText = YDCode.Rand.Str(5).Trim();
         Session["CaptchaImageText"] = strCaptchaImageText;
         string       CaptchaImageText = strCaptchaImageText;
         MemoryStream ms = Rand.CreateCodeImg(CaptchaImageText);
         Response.ClearContent();
         Response.ContentType = "image/Gif";
         Response.BinaryWrite(ms.ToArray());
     }
 }