C#中圖片與BASE64碼互相轉換

//圖片 轉為    base64編碼的文本
        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog dlg = new OpenFileDialog();
            dlg.Multiselect = true;
            dlg.Title = "選擇要轉換的圖片";
            dlg.Filter = "Image files (.jpg;.bmp;.gif;.png)|.jpg.jpeg;.gif;.bmp|AllFiles (.)|.";
            if (DialogResult.OK == dlg.ShowDialog())
            {
                for (int i = 0; i < dlg.FileNames.Length; i++)
                {
                    ImgToBase64String(dlg.FileNames[i].ToString());
                }
            }
        }
        //圖片 轉為    base64編碼的文本
        private void ImgToBase64String(string Imagefilename)
        {
            try
            {
                Bitmap bmp = new Bitmap(Imagefilename);
                this.pictureBox1.Image = bmp;
                FileStream fs = new FileStream(Imagefilename + ".txt", FileMode.Create);
                StreamWriter sw = new StreamWriter(fs);


            MemoryStream ms = new MemoryStream();
            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
            byte[] arr = new byte[ms.Length];
            ms.Position = 0;
            ms.Read(arr, 0, (int)ms.Length);
            ms.Close();
            String strbaser64 = Convert.ToBase64String(arr);
            sw.Write(strbaser64);


            sw.Close();
            fs.Close();
           // MessageBox.Show("轉換成功!");
        }
        catch (Exception ex)
        {
            MessageBox.Show("ImgToBase64String 轉換失敗\nException:" + ex.Message);
        }
    }


    //base64編碼的文本 轉為    圖片
    private void button2_Click(object sender, EventArgs e)
    {
        OpenFileDialog dlg = new OpenFileDialog();
        dlg.Multiselect = true;
        dlg.Title = "選擇要轉換的base64編碼的文本";
        dlg.Filter = "txt files|*.txt";
        if (DialogResult.OK == dlg.ShowDialog())
        {
            for (int i = 0; i < dlg.FileNames.Length; i++)
            {
                Base64StringToImage(dlg.FileNames[i].ToString());
            }

        }
    }
    //base64編碼的文本 轉為    圖片
    private void Base64StringToImage(string txtFileName)
    {
        try
        {
            FileStream ifs = new FileStream(txtFileName, FileMode.Open, FileAccess.Read);
            StreamReader sr = new StreamReader(ifs);


            String inputStr = sr.ReadToEnd();
            byte[] arr = Convert.FromBase64String(inputStr);
            MemoryStream ms = new MemoryStream(arr);
            Bitmap bmp = new Bitmap(ms);


            //bmp.Save(txtFileName + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
            //bmp.Save(txtFileName + ".bmp", ImageFormat.Bmp);
            //bmp.Save(txtFileName + ".gif", ImageFormat.Gif);
            //bmp.Save(txtFileName + ".png", ImageFormat.Png);
            ms.Close();
            sr.Close();
            ifs.Close();
            this.pictureBox2.Image = bmp;
            if (File.Exists(txtFileName))
            {
                File.Delete(txtFileName);
            }
            //MessageBox.Show("轉換成功！");
        }
        catch (Exception ex)
        {
            MessageBox.Show("Base64StringToImage 轉換失敗\nException：" + ex.Message);
        }
    } </pre>