Ошибка при добавлении ImageField в модель - Python

Unhandled exception in thread started by <function wrapper at 0x0000000002F3FC18>
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\django\utils\autoreload.py", line 93, in wrapper
    fn(*args, **kwargs)
  File "C:\Python27\lib\site-packages\django\core\management\commands\runserver.py", line 101, in inner_run
    self.validate(display_num_errors=True)
  File "C:\Python27\lib\site-packages\django\core\management\base.py", line 310, in validate
    num_errors = get_validation_errors(s, app)
  File "C:\Python27\lib\site-packages\django\core\management\validation.py", line 113, in get_validation_errors
    from django.utils.image import Image
  File "C:\Python27\lib\site-packages\django\utils\image.py", line 154, in <module>
    Image, _imaging, ImageFile = _detect_image_library()
  File "C:\Python27\lib\site-packages\django\utils\image.py", line 108, in _detect_image_library
    _("Neither Pillow nor PIL could be imported: %s") % err
django.core.exceptions.ImproperlyConfigured

class Article(models.Model):
    class Meta():
        verbose_name = "Статья"
        verbose_name_plural = "статьи"
    article_author = models.ForeignKey(User, related_name='articles', verbose_name='Автор')
    article_title = models.CharField(max_length=50, verbose_name='Заголовок')
    article_text = models.TextField(verbose_name='Содержание')
    article_picture = models.ImageField(upload_to='/uploads/', verbose_name='Изображение', blank=True)
    article_date = models.DateTimeField(verbose_name='Дата публикации')
    article_likes = models.PositiveIntegerField(default=0)
    article_category = models.ForeignKey(Category, related_name='posts', verbose_name='Категория')
    def __unicode__(self):
        return self.article_title