在URL加密访问情况下如何传入图片裁切参数？

                各位大神，在URL加密访问情况下如何传入图片裁切参数？      
                
                DateTime expirationDate = DateTime.Now.AddMinutes(10);
                GeneratePresignedUriRequest generateRequest = new GeneratePresignedUriRequest(item.BucketName, item.Key);
                Dictionary<string, string> dicParam = new Dictionary<string, string>();
                generateRequest.QueryParams = dicParam;
                generateRequest.Expiration = expirationDate;
                var url = client.GeneratePresignedUri(generateRequest).ToString();