def normalize(
        self,
        image: np.ndarray,
        data_format: Optional[Union[str, ChannelDimension]] = None,
        input_data_format: Optional[Union[str, ChannelDimension]] = None,
    ) -> np.ndarray:
        """
        Normalizes an images' pixel values to between [-1, 1].

        Args:
            image (`np.ndarray`):
                Image to normalize.
            data_format (`str` or `ChannelDimension`, *optional*):
                The channel dimension format of the image. If not provided, it will be the same as the input image.
            input_data_format (`ChannelDimension` or `str`, *optional*):
                The channel dimension format of the input image. If not provided, it will be inferred.
        """
        image = rescale(image=image, scale=1 / 127.5, data_format=data_format, input_data_format=input_data_format)
        image = image - 1
        return image

        Normalizes an images' pixel values to between [-1, 1].

        Args:
            image (`np.ndarray`):
                Image to normalize.
            data_format (`str` or `ChannelDimension`, *optional*):
                The channel dimension format of the image. If not provided, it will be the same as the input image.
            input_data_format (`ChannelDimension` or `str`, *optional*):
                The channel dimension format of the input image. If not provided, it will be inferred.
        
dpkd/transformers/src/transformers/models/imagegpt/image_processing_imagegpt.py