Add binary Image to existing PDF using iTextSharp in ASP.Net

I have succeeded in making it work. Here is my code.

On page load, the uploaded pdf file will be displayed in literal control and a QR code will be generated and bind in image control

 protected void Page_Load(object sender, EventArgs e)
    {
        BindCardAndQR();
    }
    private void BindCardAndQR()
    {
        if (Session["paperinv"] != null)
        {
            int id = Convert.ToInt32(Session["paperinv"]);

            string sql = "SELECT * FROM tableinvoice WHERE Id = @Id";
            SqlParameter[] parameters = new[] {
                    new SqlParameter("@Id", id)
                };

            // Bind Image3 for Card Image
            DataTable dt = SelectFromDatabase(sql, parameters);
            if (dt.Rows.Count > 0)
            {
            string embed = "<object data=\"{0}{1}\" type=\"application/pdf\"></object>";
            ltEmbed.Text = string.Format(embed, ResolveUrl("Handler.ashx?Id="), id);

            byte[] QRBytes = GetQRCodeBytes(Server.MapPath("~/PDFprint.aspx") + "?Id=" + id);
            Image1.ImageUrl = "data:image/jpg;base64," + Convert.ToBase64String(QRBytes);
            }
        }
    }
    public byte[] GetQRCodeBytes(string url)
    {
        //QR code generated here
        QRCodeEncoder encoder = new QRCodeEncoder();
        Bitmap bi = encoder.Encode(url);
        MemoryStream tmpSteam = new MemoryStream();
        bi.Save(tmpSteam, ImageFormat.Jpeg);
        return tmpSteam.ToArray();
    }

Then on Button click, the QR code generated in image control will be attached to the uploaded pdf for downloading or printing

 protected void btnPrinnt_Click(object sender, EventArgs e)
    {
        if (Session["paperinv"] != null)
        {
            int id = Convert.ToInt32(Session["paperinv"]);

            string sql = "SELECT * FROM tableinvoice WHERE Id = @Id";
            SqlParameter[] parameters = new[] {
                    new SqlParameter("@Id", id)
                };

            // Bind Image3 for Card Image
            DataTable dt = SelectFromDatabase(sql, parameters);
            if (dt.Rows.Count > 0)
            {
                string embed = "<object data=\"{0}{1}\" type=\"application/pdf\"></object>";
                ltEmbed.Text = string.Format(embed, ResolveUrl("Handler.ashx?Id="), id);

                byte[] QRBytes = GetQRCodeBytes(Server.MapPath("~/PDFprint.aspx") + "?Id=" + id);
                Image1.ImageUrl = "data:image/jpg;base64," + Convert.ToBase64String(QRBytes);

                iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(QRBytes);

                byte[] pdfbytes = (byte[])dt.Rows[0]["Data"];

                using (MemoryStream memoryStream = new MemoryStream())
                {
                    var reader = new PdfReader(pdfbytes);
                    var stamper = new PdfStamper(reader, memoryStream);
                    var pdfContentByte = stamper.GetOverContent(1);
                    image.SetAbsolutePosition(10, reader.GetPageSize(1).Height - 100);
                    pdfContentByte.AddImage(image);
                    stamper.Close();
                    byte[] bytess = memoryStream.ToArray();
                    memoryStream.Close();

                    Response.Clear();
                    Response.ContentType = "application/pdf";
                    Response.AddHeader("Content-Disposition", "attachment; filename=Invoice.pdf");
                    Response.ContentType = "application/pdf";
                    Response.Buffer = true;
                    Response.Cache.SetCacheability(HttpCacheability.NoCache);
                    Response.BinaryWrite(bytess);
                    Response.End();
                }
            }
        }
    }
    public static DataTable SelectFromDatabase(string sql, SqlParameter[] parameters)
    {
        using (SqlConnection con = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\\Dataregister.mdf;Integrated Security=True"))
        {

            using (SqlCommand cmd = new SqlCommand(sql, con))
            {
                if (parameters != null)
                {
                    cmd.Parameters.AddRange(parameters);
                }

                using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
                {
                    DataTable dt = new DataTable();
                    sda.Fill(dt);
                    return dt;
                }
            }
        }
    }