def put_img(board, img, center):
    """put a image into a big board image with the anchor center."""
    center_x, center_y = center
    img_h, img_w, _ = img.shape
    xmin, ymin = int(center_x - img_w // 2), int(center_y - img_h // 2)
    board[ymin:ymin + img_h, xmin:xmin + img_w, :] = img
    return board