Lenni

import cv2
import numpy as np


def extract_qr(filename):
    image = cv2.imread(filename)
    image = cv2.resize(image, None, fx=1 / 10, fy=1 / 10, interpolation=cv2.INTER_AREA)
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    gray = 255 - gray
    thresh = cv2.threshold(gray, 0, 255, cv2.THRESH_BINARY + cv2.THRESH_OTSU)[1]