cv2. faceDetection

import cv2


cascPath = './haarcascade_frontalface_alt.xml'
faceCascade = cv2.CascadeClassifier(cascPath)


cap = cv2.VideoCapture(0)

cap.set(3,640)

cap.set(4,480)

while True:

ret,img = cap.read()
# frame = cv2.flip(frame,-1)#旋转屏幕
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

faces = faceCascade.detectMultiScale(gray,scaleFactor=1.2,minNeighbors=5,minSize=(20,20))

for (x,y,w,h) in faces:

cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)

roi_gray = gray[y:y+h, x:x+w]

roi_color = img[y:y+h, x:x+w]


cv2.imshow('video',img)


k = cv2.waitKey(30) & 0xff
    if k == 27:  #press 'ESC' to quit
        break

cap.release()

cv2.destroyAllWindows()