def transform_pil_image(self, pil_image):
        '''
        Uses :py:meth:`PIL.Image.Image.transform` to scale
        down the image.

        Based on `this stackoverflow discussions <http://stackoverflow.com/a/940368/907060>`_, uses
        :attr:`PIL.Image.ANTIALIAS`
        '''
        max_width = min(self.dimensions[0] or float('inf'), pil_image.size[0])
        max_height = min(self.dimensions[1] or float('inf'), pil_image.size[1])
        max_dimensions = (max_width, max_height)

        pil_image.thumbnail(max_dimensions, Image.ANTIALIAS)
        return pil_image