Как экспортировать веб-страницу в excel с помощью ASP.NET

When this code run, everything is ok except images. They aren't coming to excel. How can I do it?

Response.Clear();
 Response.ContentType = "application/vnd.msexcel";
 Response.AddHeader("content-disposition", "attachment; filename=rapor.xls");
 Response.ContentEncoding = System.Text.Encoding.Default;
 System.IO.StringWriter stringWrite = new System.IO.StringWriter();
 System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
 panel1.RenderControl(htmlWrite);
 Response.Write(stringWrite.ToString());
 Response.End();