# models.py

    def thumb_(self):
        tiny = path.join(path.dirname(self.get_img_filename()), 'thumb_' + path.basename(self.get_img_filename()))
        if not path.exists(tiny):
            im = Image.open(self.get_img_filename())
            im.thumbnail(TINY_SIZE, Image.ANTIALIAS)
            im.save(tiny, 'JPEG')
        tiny_url = path.join(settings.MEDIA_URL, path.dirname(self.img), 'thumb_' + path.basename(self.img))
        ancore = '<a href="%s" target="_blank"><img src="%s" alt="thumbnail of %s"/></a>' % (self.get_img_url(), tiny_url, self.alt)
        return ancore
    thumb_.allow_tags = True
    thumb_.short_description = _('thumb')

    class Admin:
        list_display = ('product', 'thumb_', 'alt')