def _trim(image):
    """Trim a PIL image and remove white space."""
    background = PIL.Image.new(image.mode, image.size, image.getpixel((0, 0)))
    diff = PIL.ImageChops.difference(image, background)
    diff = PIL.ImageChops.add(diff, diff, 2.0, -100)
    bbox = diff.getbbox()
    if bbox:
        image = image.crop(bbox)
    return image