Export GridView with Images from database to Word Excel and PDF Formats

protected void btnExportPDF_Click(object sender, EventArgs e)
        {
Response.ContentType = "application/pdf";
            Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.pdf");
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            StringWriter sw = new StringWriter();
            HtmlTextWriter hw = new HtmlTextWriter(sw);
            C1GridView1_listview.AllowPaging = false;
            C1GridView1_listview.DataBind();
            C1GridView1_listview.RenderControl(hw);
            C1GridView1_listview.HeaderRow.Style.Add("width", "15%");
            C1GridView1_listview.HeaderRow.Style.Add("font-size", "10px");
            C1GridView1_listview.Style.Add("text-decoration", "none");
            C1GridView1_listview.Style.Add("font-family", "Arial, Helvetica, sans-serif;");
            C1GridView1_listview.Style.Add("font-size", "8px");
            StringReader sr = new StringReader(sw.ToString());
            Document pdfDoc = new Document(PageSize.A2, 7f, 7f, 7f, 0f);
            HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
            PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
            pdfDoc.Open();
            htmlparser.Parse(sr);//this is error line
            pdfDoc.Close();
            Response.Write(pdfDoc);
            Response.End();

}