def center_reposition(center, frame):
    """Reposition center so that (0, 0) is in the middle of the frame and y is
    pointing up instead of the OpenCV standard where (0, 0) is at the top left
    and y is pointing down.

    :param center: OpenCV center (x, y)
    :param frame: Frame to reposition center within
    :return:
    """
    if center is None:
        return None
    # convert so (0, 0) is at the middle bottom of the frame
    center_x = center[0] - int(round(frame.shape[1] / 2))
    center_y = int(round(frame.shape[0] / 2)) - center[1]

    return center_x, center_y