def METHOD_NAME(args, img_path, detector, pose_estimator):
    """Visualize predicted keypoints of one image in openpose format."""
    # predict bbox
    scope = detector.cfg.get('default_scope', 'mmdet')
    if scope is not None:
        init_default_scope(scope)
    det_result = inference_detector(detector, img_path)
    pred_instance = det_result.pred_instances.cpu().numpy()
    bboxes = np.concatenate(
        (pred_instance.bboxes, pred_instance.scores[:, None]), axis=1)
    bboxes = bboxes[np.logical_and(pred_instance.labels == args.det_cat_id,
                                   pred_instance.scores > args.bbox_thr)]
    bboxes = bboxes[nms(bboxes, args.nms_thr), :4]
    # predict keypoints
    pose_results = inference_topdown(pose_estimator, img_path, bboxes)
    data_samples = merge_data_samples(pose_results)
    # concatenate scores and keypoints
    keypoints = np.concatenate(
        (data_samples.pred_instances.keypoints,
         data_samples.pred_instances.keypoint_scores.reshape(-1, 17, 1)),
        axis=-1)
    # compute neck joint
    neck = (keypoints[:, 5] + keypoints[:, 6]) / 2
    if keypoints[:, 5, 2] < args.kpt_thr or keypoints[:, 6, 2] < args.kpt_thr:
        neck[:, 2] = 0
    # 17 keypoints to 18 keypoints
    new_keypoints = np.insert(keypoints[:, ], 17, neck, axis=1)
    # mmpose format to openpose format
    openpose_idx = [15, 14, 17, 16, 2, 6, 3, 7, 4, 8, 12, 9, 13, 10, 1]
    mmpose_idx = [1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17]
    new_keypoints[:, openpose_idx, :] = new_keypoints[:, mmpose_idx, :]
    # show the results
    img = mmcv.imread(img_path, channel_order='rgb')
    # black background
    black_img = np.zeros_like(img)
    num_instance = new_keypoints.shape[0]
    # draw keypoints
    for i, j in product(range(num_instance), range(num_openpose_kpt)):
        x, y, conf = new_keypoints[i][j]
        if conf > args.kpt_thr:
            cv2.circle(black_img, (int(x), int(y)), 4, colors[j], thickness=-1)
    # draw links
    cur_black_img = black_img.copy()
    for i, link_idx in product(range(num_instance), range(num_link)):
        conf = new_keypoints[i][np.array(limb_seq[link_idx]) - 1, 2]
        if np.sum(conf > args.kpt_thr) == 2:
            Y = new_keypoints[i][np.array(limb_seq[link_idx]) - 1, 0]
            X = new_keypoints[i][np.array(limb_seq[link_idx]) - 1, 1]
            mX = np.mean(X)
            mY = np.mean(Y)
            length = ((X[0] - X[1])**2 + (Y[0] - Y[1])**2)**0.5
            angle = math.degrees(math.atan2(X[0] - X[1], Y[0] - Y[1]))
            polygon = cv2.ellipse2Poly(
                (int(mY), int(mX)), (int(length / 2), stickwidth), int(angle),
                0, 360, 1)
            cv2.fillConvexPoly(cur_black_img, polygon, colors[link_idx])
    black_img = cv2.addWeighted(black_img, 0.4, cur_black_img, 0.6, 0)
    # save image
    out_file = 'openpose_' + os.path.splitext(
        os.path.basename(img_path))[0] + '.png'
    cv2.imwrite(out_file, black_img[:, :, [2, 1, 0]])