pi_face_cascade

#Load a cascade file for detecting faces
face_cascade = cv2.CascadeClassifier('/home/pi/Desktop/opencv/haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('/home/pi/Desktop/opencv/haarcascade_eye.xml')

#Convert to grayscale
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

#Look for faces in the image using the loaded cascade file
faces = face_cascade.detectMultiScale(gray, 1.3, 5)

print "Found "+str(len(faces))+" face(s)"

#Draw a rectangle around every found face

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]

        eyes = eye_cascade.detectMultiScale(roi_gray)
        for (ex,ey,ew,eh) in eyes:
            cv2.rectangle(roi_color,(ex,ey),(ex+ew,ey+eh),(0,255,0),2)

#Save the result2 image
cv2.imwrite('result2.jpg',img)