import sys
sys.path.append('/usr/local/lib/python2.7/site-packages')
import cv2
import numpy as np

faceCascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')

cap = cv2.VideoCapture(0)
while(cap.isOpened()):
        ret,img = cap.read()
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        faces = faceCascade.detectMultiScale(gray, scaleFactor=1.3, minNeighbors=5, minSize=(30, 30), flags = cv2.CASCADE_SCALE_IMAGE)

        for (x, y, w, h) in faces:
                cv2.rectangle(img, (x, y), (x+w, y+h), (0, 255, 0), 2)

        cv2.imshow('Video', img)

        k=cv2.waitKey(10)
        if k== 27:
                break

cap.release()
cv2.destroyAllWindows()