Animation 来自base64数据字符串的动画gif和错误结果

您好im上传从输入形式的数据：图像，它的作品以及png和jpg 但是我不能用GIF来工作

  <input value="data:image/gif;base64,...................................." type="hidden" /> 

function ImageUploadString($data_string) 
{
 $data_string = str_replace('data:image/gif;base64,', '', $data_string); 
 $data_string = base64_decode($data_string);   // decode image from base64
 $image = imagecreatefromstring($data_string);

 if ($image !== false) {
 $random_imagename = str_shuffle(MD5(microtime()));
 $extention = "gif";
 $ufname = 'folder/'.$random_imagename.'.'.$extention;

$image = @imagecreatefromgif($image); /* Attempt to open */

 if (!$image) {
 imagedestroy($image);
  die('gif error');
   }

 imagegif($image, $ufname);

  }
     }

  $imagebase = "data:image/gif;base64,..........................................";
  ImageUploadString($imagebase);