In Reporting Services, increase the quality of the background image above 96 dpi

I found a webpage which explain how to export PDF with a good dpi. http://codeproject.com/Articles/95750/High-fidelity-printing-through-the-SSRS-Report-Vie

The key is to initialize the deviceInfo string with a xml code

       var sb = new System.Text.StringBuilder(1024);
       var xr = System.Xml.XmlWriter.Create(sb);
       xr.WriteStartElement("DeviceInfo");
       xr.WriteElementString("DpiX", "296");
       xr.WriteElementString("DpiY", "296");
       xr.Close();

        deviceInfo = sb.ToString();

        rsExec.SetExecutionParameters(parameters, "fr-fr");

        results = rsExec.Render(format, deviceInfo,
                  out extension, out encoding,
                  out mimeType, out warnings, out streamIDs);

In this case, this solution works. I can generate a pdf file with the good dpi BUT the print button with activex doesn't work (this shouldn't be a problem) and the export button either. I have to add a download button to print. that's a partial solution imho