Parses crop into a tuple usable by the crop function.

        :param crop: String with the crop settings.
        :param original_size: A tuple of size of the image that should be cropped.
        :param size: A tuple of the wanted size.
        :return: Tuple of two integers with crop settings
        :rtype: tuple

def parse_crop(self, crop, original_size, size):
        """
        Parses crop into a tuple usable by the crop function.

        :param crop: String with the crop settings.
        :param original_size: A tuple of size of the image that should be cropped.
        :param size: A tuple of the wanted size.
        :return: Tuple of two integers with crop settings
        :rtype: tuple
        """
        if crop is None:
            return None

        crop = crop.split(' ')
        if len(crop) == 1:
            crop = crop[0]
            x_crop = 50
            y_crop = 50
            if crop in CROP_ALIASES['x']:
                x_crop = CROP_ALIASES['x'][crop]
            elif crop in CROP_ALIASES['y']:
                y_crop = CROP_ALIASES['y'][crop]

        x_offset = self.calculate_offset(x_crop, original_size[0], size[0])
        y_offset = self.calculate_offset(y_crop, original_size[1], size[1])
        return int(x_offset), int(y_offset)