Почему mime_types не правильно определяется?

      $mime_types = ['image/bmp', 'image/gif', 'image/jpeg', 'image/png'];

      Validator::extend('is_image_array', function($attribute, $values, $params, $validator) use ($mime_types) {

          foreach ($values as $k => $value) {
              $f = finfo_open();

              $result = finfo_buffer($f, base64_decode($value), FILEINFO_MIME_TYPE);

              dd($f, $value,$result, $mime_types);
              if ( !in_array($result, $mime_types)){
                  return false;
              }
          }
          return true;
      });