private void AddWaterMark(Aspose.Pdf.Page page)
        {
            try
            {
                //create e new artifact...
                Artifact art = new Artifact(Artifact.ArtifactType.Background, Artifact.ArtifactSubtype.Watermark);

                //get the image to assign to watermark...
                FileStream imageStream = new FileStream(Server.MapPath("~/Images/aspose.jpg"), FileMode.Open);

                //add image to the resources of the page...
                page.Resources.Images.Add(imageStream);
                XImage ximage = page.Resources.Images[page.Resources.Images.Count];
                //set image of the watermark...
                art.SetImage(imageStream);
                //set the position of the watermark on the page...
                art.ArtifactHorizontalAlignment = HorizontalAlignment.Center;
                art.ArtifactVerticalAlignment = VerticalAlignment.Center;
                //wart.Rotation = 45; //to rotate the watermark...
                art.Opacity = 0.1;

                //add watermark in page
                page.Artifacts.Add(art);
            }
            catch (Exception exp)
            {
                msg.Text = "<div class='alert alert-danger'><button data-dismiss='alert' class='close' type='button'>×</button>Exception Occured:" + exp.Message + "</div>";
            }
        }