def preprocess(image):
    image = cv2.resize(image, (128, 72))
    if len(image.shape) == 3 and image.shape[-1] == 3:
        image = cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)
        image = np.expand_dims(image, -1)
    elif len(image.shape) == 3 and image.shape[-1] == 4:
        image = cv2.cvtColor(image, cv2.COLOR_RGBA2GRAY)
        image = np.expand_dims(image, -1)
    if len(image.shape) == 2:
        image = np.expand_dims(image, -1)
    return image