BitMap 图片格式与Base64Image格式互转方法

  /// <summary>
        /// 图片转为base64编码的字符串
        /// </summary>
        /// <param name="Imagefilename"></param>
        /// <returns></returns>
        protected 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 = 0;
                ms.Read(arr,(int)ms.Length);
                ms.Close();
                return Convert.ToBase64String(arr);
            }
            catch (Exception ex)
            {
                return null;
            }
        }

        /// <summary>
        /// threeebase64编码的字符串转为图片
        /// </summary>
        /// <param name="strbase64"></param>
        /// <returns></returns>
        protected Bitmap Base64StringToImage(string strbase64)
        {
            try
            {
                byte[] arr = Convert.FromBase64String(strbase64);
                MemoryStream ms = new MemoryStream(arr);
                Bitmap bmp = new Bitmap(ms);
                bmp.Save(@"d:test.jpg",System.Drawing.Imaging.ImageFormat.Jpeg);
                //bmp.Save(@"d:"test.bmp",ImageFormat.Bmp);
                //bmp.Save(@"d:"test.gif",ImageFormat.Gif);
                //bmp.Save(@"d:"test.png",ImageFormat.Png);
                ms.Close();
                return bmp;
            }
            catch (Exception ex)
            {
                return null;
            }
        }