视频实时人脸检测功能已经做出来了就差人脸覆盖了，求助，我的代码如下，请各位大神直接在我的代码里加入人脸覆盖代码即可，谢谢；
import cv2
face_cascade = cv2.CascadeClassifier('E:\openCV\opencv\sources/data/haarcascades/haarcascade_frontalface_alt2.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()
