Illegal characters in path. while exporting image which is coming from server to PDF using Itextsharp

Question

I am using Itextsharp to generate PDF while exporting i have a image which is coming from server which is in byte format . It shows Illegal characters in path. please help me.

.aspx

<asp:Image ID="img_dealer" runat="server" Width="150px" Height="150px" />

.cs

 if (dt.Rows[0]["Photo"].ToString().Trim() != null || dt.Rows[0]["Photo"].ToString().Trim() != "")
        {
          Session["Photo"] = (byte[])dt.Rows[0]["Photo"];
          string encrypt_id = Utilities.encrypt(Utilities.convt("3"), ConfigurationManager.AppSettings["AadharEncKey"]);                   
          img_dealer.ImageUrl = "Image.aspx?id=" + encrypt_id + "";
            Session["ImageUrl"] = "Image.aspx?id=" + encrypt_id + "";
        }

private byte[] GetImage(string RegNO)
    {
        if (con.State == ConnectionState.Closed)
            con.Open();            
        string sTSQL = "select Photo from FL_Form_A1 where Reg_No='" + RegNO + "'";
        SqlCommand objCmd = new SqlCommand(sTSQL, con);
        objCmd.CommandType = CommandType.Text;
        object result = objCmd.ExecuteScalar();
        con.Close();
        return (byte[])result;
    } 

protected void export_click(object sender, EventArgs e)
    {
        string strid = Utilities.Decrypt(Request.QueryString["lbid1122"].ToString().Trim().Replace(" ", "+"), ConfigurationManager.AppSettings["AadharEncKey"]);
        string appPath = HttpContext.Current.Request.ApplicationPath;
        govlogo.ImageUrl = Server.MapPath(".") + "\\Image\\kar_logo4.jpg";       
        iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(GetImage(strid));           
        string path = Server.MapPath(appPath + "eSign/eSignfiles/" + strid + ".pdf");
        Response.ContentType = "application/pdf";
        Response.AddHeader("content-disposition", "attachment;filename=" + strid + ".pdf");
        Response.Cache.SetCacheability(HttpCacheability.NoCache);        
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);
        this.Page.RenderControl(hw);
        dynamic output = new FileStream(path, FileMode.Create);
        StringReader sr = new StringReader(sw.ToString());      
        Document pdfDoc = new Document(PageSize.A4, 88f, 88f, 10f, 10f);
        HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
        PdfWriter.GetInstance(pdfDoc, output);
        pdfDoc.Open();
        //pdfDoc.Add(img);
        htmlparser.Parse(sr);
        pdfDoc.Close();
    }