OpenXml PowerPoint to Jpg

OpenXml PowerPoint to Jpg

var fileName = Server.MapPath("/Content/test_small.pptx");
            var presentation = PresentationDocument.Open(fileName, true);
            int i = 1;
            ViewBag.Link = null;
            foreach (var slide in presentation.PresentationPart.SlideParts)
            {
                var imagePart = (ImagePart)slide.GetPartById("rId2");
                var img = Image.FromStream(imagePart.GetStream());
                var bmp = new Bitmap(1920, 1080);
                using (var graph = Graphics.FromImage(bmp))
                {
                    var imageSize = new Rectangle(0, 0, 1920, 1080);
                    graph.FillRectangle(Brushes.White, imageSize);
                }

                var xposition = (1920 - img.Width) / 2;
                var yposition = (1080 - img.Height) / 2;
                var zemin = new Bitmap(bmp);
                var g = Graphics.FromImage(zemin);
                g.SmoothingMode = SmoothingMode.HighQuality;
                g.PixelOffsetMode = PixelOffsetMode.HighQuality;
                g.CompositingQuality = CompositingQuality.HighQuality;
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.DrawImage(img, xposition, yposition, img.Width, img.Height);
                var filename = "powerpoint_" + i++ + ".jpg";
                zemin.Save(Server.MapPath("~/Content/" + filename), ImageFormat.Jpeg);
                g.Dispose();
                zemin.Dispose();
                ViewBag.Link += "<a href='/Content/" + filename + "' target='_blank'>"+ filename + "</a></br>";
            }
            presentation.Close();