def __init__(self,
                 size=None,
                 size_divisor=32,
                 pad_mode=0,
                 offsets=None,
                 fill_value=(127.5, 127.5, 127.5)):
        """
        Pad image to a specified size or multiple of size_divisor.
        Args:
            size (int, Sequence): image target size, if None, pad to multiple of size_divisor, default None
            size_divisor (int): size divisor, default 32
            pad_mode (int): pad mode, currently only supports four modes [-1, 0, 1, 2]. if -1, use specified offsets
                if 0, only pad to right and bottom. if 1, pad according to center. if 2, only pad left and top
            offsets (list): [offset_x, offset_y], specify offset while padding, only supported pad_mode=-1
            fill_value (bool): rgb value of pad area, default (127.5, 127.5, 127.5)
        """
        super(Pad, self).__init__()

        if not isinstance(size, (int, Sequence)):
            raise TypeError(
                "Type of target_size is invalid when random_size is True. \
                            Must be List, now is {}".format(type(size)))

        if isinstance(size, int):
            size = [size, size]

        assert pad_mode in [
            -1, 0, 1, 2
        ], 'currently only supports four modes [-1, 0, 1, 2]'
        if pad_mode == -1:
            assert offsets, 'if pad_mode is -1, offsets should not be None'

        self.size = size
        self.size_divisor = size_divisor
        self.pad_mode = pad_mode
        self.fill_value = fill_value
        self.offsets = offsets

        Pad image to a specified size or multiple of size_divisor.
        Args:
            size (int, Sequence): image target size, if None, pad to multiple of size_divisor, default None
            size_divisor (int): size divisor, default 32
            pad_mode (int): pad mode, currently only supports four modes [-1, 0, 1, 2]. if -1, use specified offsets
                if 0, only pad to right and bottom. if 1, pad according to center. if 2, only pad left and top
            offsets (list): [offset_x, offset_y], specify offset while padding, only supported pad_mode=-1
            fill_value (bool): rgb value of pad area, default (127.5, 127.5, 127.5)
        
ppdet/data/transform/operators.py