def normalize_image(image):
    """
    Normalize image array from 0 ~ 255
    to 0.0 ~ 1.0

    :param image: origin input image
            numpy image array with dtype=float, 0.0 ~ 255.0
    :return image: numpy image array with dtype=float, 0.0 ~ 1.0
    """
    image = image / 255.0
    return image