def draw_axis(img, charuco_corners, charuco_ids, board):
    vecs = np.load("./calib.npz")  # I already calibrated the camera
    mtx, dist, _, _ = [vecs[i] for i in ('mtx', 'dist', 'rvecs', 'tvecs')]
    ret, rvec, tvec = cv2.aruco.estimatePoseCharucoBoard(
        charuco_corners, charuco_ids, board, mtx, dist)
    if ret is not None and ret is True:
        cv2.aruco.drawAxis(img, mtx, dist, rvec, tvec, 0.1)