python opencv人脸检测提取及保存方法

import cv2
save_path = 'F:\\face_photo_save\\chenym\\'
cascade = cv2.CascadeClassifier("D:\\opencv249\\opencv\\sources\\data\\haarcascades\\haarcascade_frontalface_alt_tree.xml")
cap = cv2.VideoCapture(0)
i = 0
while True:
 ret,frame = cap.read()
 gray = cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
 rect = cascade.detectMultiScale(gray,scaleFactor=1.3,minNeighbors=9,minSize=(50,50),flags = cv2.cv.CV_HAAR_SCALE_IMAGE)
 print "rect",rect
 if not rect is (): 
  for x,y,z,w in rect:
   roiImg = frame[y:y+w,x:x+z]
   cv2.imwrite(save_path+str(i)+'.jpg',roiImg)
   cv2.rectangle(frame,(x,y),(x+z,y+w),(0,0,255),2)
   i +=1
 cv2.imshow('frame',frame)  
 if cv2.waitKey(1) &0xFF == ord('q'):
  break
cap.release()
cv2.destroyAllWindows()