def normalize_hu(image):
    """Rescale an image such that tissue with Houndsfield units between air and bone is scaled to between 0 and 1.
    Tissue that is not that dense is clipped accordingly.

    Args:
        image: numpy.array

    Returns: numpy.array

    """
    MIN_BOUND = -1000.0  # Air
    MAX_BOUND = 400.0  # Bone
    image = (image - MIN_BOUND) / (MAX_BOUND - MIN_BOUND)
    image[image > 1] = 1.
    image[image < 0] = 0.
    return image