from typing import Tuple


def pad_frame(frame_data: bytes, size: Tuple[int, int]) -> bytes:
    """Pads frame data to fit the size.

    Args:
        frame_data (bytes): Any byte string
        size (Tuple[int, int]): Resolution of the image

    Returns:
        bytes: Padded frame data
    """
    return frame_data.ljust(size[0] * size[1] * 3, b"\x00")