Convert HTML file to image using web browser in windows NT service

Question

 private static void StartBrowser(string source)
        {
            var th = new Thread(() =>
            {
                var webBrowser = new WebBrowser();
                webBrowser.ScrollBarsEnabled = false;
                webBrowser.DocumentCompleted += webBrowser_DocumentCompleted;
                webBrowser.DocumentText = source;
                Application.Run();
            });
            th.SetApartmentState(ApartmentState.STA);
            th.Start();
        }

        static void webBrowser_DocumentCompleted(object sender,WebBrowserDocumentCompletedEventArgs e)
        {
            var webBrowser = (WebBrowser)sender;
            using (Bitmap bitmap = new Bitmap(576,384))
            {
                webBrowser.DrawToBitmap(bitmap,new System.Drawing.Rectangle(0, 0, bitmap.Width, bitmap.Height));
                bitmap.Save(@"images/" + "xxx.jpg",System.Drawing.Imaging.ImageFormat.Jpeg);
            }
        }

Hi Guys,

I am trying to print out an HTML file in a windows service by using the windows application web browser. For some reason, I cannot get a clear image, it draws only 25% of the image.

Note:- There is a barcode image in the upper right corner.