public static void GenerateCanvas(string imgSaveName, int canvasWidth, int canvasHeight, string imgData)        {            try            {                if (string.IsNullOrEmpty(imgData)) return;                if (imgData.StartsWith("data:image/png;base64") == false) return;                var base64 = imgData.Substring(22);                byte[] bytes = Convert.FromBase64String(base64);                MemoryStream memStream = new MemoryStream(bytes);                BinaryFormatter binFormatter = new BinaryFormatter();                var img = System.Drawing.Image.FromStream(memStream);                img.Save(imgSaveName);            }            catch (Exception ex)            {            }        }