Opencv的人脸检测

import cv2
cascPath=r"C:\\Users\86138\\anaconda3\\envs\\jupy\\Lib\site-packages\\cv2\data\\haarcascade_frontalface_alt2.xml"
faceCascade=cv2.CascadeClassifier(cascPath)
cap=cv2.VideoCapture(0)
while(True):
    ret,img=cap.read()
    faces=faceCascade.detectMultiScale(img,1.2,2,cv2.CASCADE_SCALE_IMAGE,(20,20))
    for (x,y,w,h) in faces:
        img=cv2.rectangle(img,(x,y),(x+w,y+h),(0,255,0),2)
    cv2.imshow(u"Detect faces",img)

    key=cv2.waitKey(1)
    if key&0xFF==ord(‘q‘) or key==27:
        break
cv2.destroyAllWindows()
cap.release()