How to generate thumbnail images for PDF documents

//see also: https://github.com/aspose-pdf/Aspose.Pdf-for-.NET/blob/master/Examples/CSharp/AsposePDF/Images/PageToPNG.cs
public class UploadController : Controller
    {
        // GET: Upload
        public ActionResult Index()
        {
            var di = new DirectoryInfo(Server.MapPath("~/Content/Images"));
            var files = di.GetFiles("*.jpg").ToList();
            return View(files);
        }
        [HttpGet]
        public ActionResult UploadFile()
        {
            return View();
        }

        [HttpPost]
        public ActionResult UploadFile(HttpPostedFileBase file)
        {
            try
            {
                if (file.ContentLength > 0)
                {
                    var fileName = Path.GetFileName(file.FileName);
                    if (fileName != null)
                    {
                        var pdfPath = Path.Combine(Server.MapPath("~/App_Data/Upload"), fileName);
                        var jpgPath = Path.ChangeExtension(Path.Combine(Server.MapPath("~/Content/Images"), fileName), "jpg");
                        Stream stream  = new MemoryStream();
                        file.InputStream.CopyTo(stream);
                        file.SaveAs(pdfPath);

                        // Open document
                        var pdfDocument = new Document(stream);

                        using (var imageStream = new FileStream(jpgPath, FileMode.Create))
                        {
                            // Create JPEG device with specified attributes
                            // Width, Height, Resolution, Quality
                            // Quality [0-100], 100 is Maximum
                            // Create Resolution object
                            var resolution = new Resolution(96);

                            var jpegDevice = new JpegDevice(96, 128, resolution, 100);
                            // ExStart:ConvertParticularPage
                            // Convert a particular page and save the image to stream
                            jpegDevice.Process(pdfDocument.Pages[1], imageStream);
                            // ExEnd:ConvertParticularPage
                            // Close stream
                            imageStream.Close();
                        }
                    }
                }
                ViewBag.Message = "File Uploaded Successfully!!";
                return View();
            }
            catch
            {
                ViewBag.Message = "File upload failed!!";
                return View();
            }
        }
    }