import cv2 as cv
import numpy as np

dico = cv.aruco.Dictionary_get(cv.aruco.DICT_7X7_250)
board=	cv.aruco.CharucoBoard_create(8, 5,  0.03455, 0.02164, dico)
detectorParams=cv.aruco.DetectorParameters_create()
detectorParams.cornerRefinementMethod = cv.aruco.CORNER_REFINE_SUBPIX
detectorParams.cornerRefinementMinAccuracy = 0.01
x = cv.imread("c:/tmp/nonerecover.png")
if x is None:
    print("Oops")
    exit()
print ("Detect ")
refAruco,ids,refus = cv.aruco.detectMarkers(image=x, dictionary=dico,parameters=detectorParams)
print("type ", type(refAruco[0]), "shape ",refAruco[0].shape, "len ",len(refAruco))
refAruco,ids,refus,recover = cv.aruco.refineDetectedMarkers(x, board, refAruco,ids,rejectedCorners=refus)
print("Refine\nRecover ",recover)
print("type ", type(refAruco[0]), "shape ",refAruco[0].shape, "len ",len(refAruco))
x = cv.imread("c:/tmp/recover.png")
if x is None:
    print("Oops")
    exit()
print ("Detect ")
refAruco,ids,refus = cv.aruco.detectMarkers(image=x, dictionary=dico,parameters=detectorParams)
print("type ", type(refAruco[0]), "shape ",refAruco[0].shape, "len ",len(refAruco))
refAruco,ids,refus,recover = cv.aruco.refineDetectedMarkers(x, board, refAruco,ids,rejectedCorners=refus)
print("Refine\nRecover ",recover)
print("type ", type(refAruco[0]), "shape ",refAruco[0].shape, "len ",len(refAruco))

Detect
type  <class 'numpy.ndarray'> shape  (1, 4, 2) len  20
Refine
Recover  None
type  <class 'numpy.ndarray'> shape  (1, 4, 2) len  20
Detect
type  <class 'numpy.ndarray'> shape  (1, 4, 2) len  19
Refine
Recover  [[6]]
type  <class 'numpy.ndarray'> shape  (4, 1, 2) len  20

   Ptr<aruco::Dictionary>  dico = aruco::getPredefinedDictionary(aruco::PREDEFINED_DICTIONARY_NAME(cv::aruco::DICT_7X7_250));
    Ptr<aruco::CharucoBoard> board = aruco::CharucoBoard::create(8, 5, 0.03455, 0.02164, dico);
    Ptr<aruco::DetectorParameters> detectorParams = aruco::DetectorParameters::create();
    detectorParams.get()->cornerRefinementMethod = aruco::CORNER_REFINE_SUBPIX;
    detectorParams.get()->cornerRefinementMinAccuracy = 0.01;

    vector< int > ids;
    vector< vector< Point2f > > refAruco, refus;
    vector<Point2f> echiquier;
    Mat x = imread("c:/tmp/nonerecover.png");
    cout << "\nDetect\n";
    aruco::detectMarkers(x, dico, refAruco, ids, detectorParams, refus);
    cout << "size refaruco : " << refAruco.size() << endl;
    cout << "size refus : " << refus.size() << endl;
    aruco::refineDetectedMarkers(x, board, refAruco, ids, refus);
    cout << "\nRefine\n";
    cout << "size refaruco : " << refAruco.size() << endl;
    cout << "size refus : " << refus.size() << endl;
    x = imread("c:/tmp/recover.png");
    refus.clear();
    ids.clear();
    refAruco.clear();

    cout << "\nDetect\n";
    aruco::detectMarkers(x, dico, refAruco, ids, detectorParams,refus);
    cout << "size refaruco : " << refAruco.size() << endl;
    cout << "size refus : " << refus.size() << endl;
    aruco::refineDetectedMarkers(x, board, refAruco, ids, refus);
    cout << "\nRefine\n";
    cout << "size refaruco : " << refAruco.size() << endl;
    cout << "size refus : " << refus.size() << endl;