python version opencv camera face real time detection method

OpenCV version 3.3.0, note that the path of the model file should be changed to the path of the model file of opencv installed by yourself, if the path is wrong, an error will be reported, generally under the path of ES3en-3.3.0 /data/haarcascades

import numpy as np
import cv2

face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
cap = cv2.VideoCapture(0)
while True:
 ret,img = cap.read()
 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
 faces = face_cascade.detectMultiScale(gray, 1.3, 5)
 for (x,y,w,h) in faces:
  cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
 cv2.imshow('img',img)  
 if cv2.waitKey(1) &0xFF == ord('q'):
  break
cap.release()
cv2.destroyAllWindows()