.NET 图片转base64

 //图片 转为    base64编码的文本
        private string ImgToBase64String(string Imagefilename)
        {
            try
            {
                Bitmap bmp = new Bitmap(Imagefilename);

                MemoryStream ms = new MemoryStream();
                bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                byte[] arr = new byte[ms.Length];
                ms.Position = ;
                ms.Read(arr, , (int)ms.Length);
                ms.Close();
                String strbaser64 = Convert.ToBase64String(arr);
                return strbaser64;
            }
            catch (Exception ex)
            {
                //LogHelper.Debug(ex);
                return "";
            }
        }