def METHOD_NAME(bg_img_path, img_shape):
    if bg_img_path is None:
        bg = 255 * np.ones(img_shape)
    elif not os.path.exists(bg_img_path):
        raise Exception('The --bg_img_path is not existed: {}'.format(
            bg_img_path))
    else:
        bg = cv2.imread(bg_img_path)
    return bg