WebHelper.cs

        public static string GetSignatureImageUrl(object transactionId)
        {
            return string.Format("{0}/{1}/signature-{2}.png",
                                 HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Authority) + HttpContext.Current.Request.ApplicationPath,
                                 ConfigurationManager.AppSettings["ImagesFolder"],
                                 transactionId);
        }