將base64字串轉換為Image圖片，現在移動端手機上，有些H5頁面上傳圖片，就是將圖片轉換為base64位，可以選擇直接儲存這個字串，也可轉換本地圖片，程式碼入下：

 var base64 = "";
 base64 = base64.Replace("data:image/png;base64,", "").Replace("data:image/jgp;base64,", "").Replace("data:image/jpg;base64,", "").Replace("data:image/jpeg;base64,", "");//將base64頭部資訊替換
  byte[] bytes = Convert.FromBase64String(base64);
  MemoryStream memStream = new MemoryStream(bytes);
  Image mImage = Image.FromStream(memStream);
 

 Bitmap bp = new Bitmap(mImage);
 MemoryStream ms = new MemoryStream();
 bp.Save(DateTime.Now.ToString("yyyyMMddHHss") + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);//注意儲存路徑