Detect face, get the boarder of face

Question

I am a new to python. I'm trying to detect face and find the boundaries of the face. How to make it? It can be a number of points that are the border of the face.

I want to obtain something like this:

Answer 1

from http://fideloper.com/facial-detection:

We can use openCV for facial detection. OpenCV is written in C, but there are bindings for Python and actually PHP.

import cv2

def detect(path):
    img = cv2.imread(path)
    cascade = cv2.CascadeClassifier("/vagrant/detect/haarcascade_frontalface_alt.xml")
    rects = cascade.detectMultiScale(img, 1.3, 4, cv2.cv.CV_HAAR_SCALE_IMAGE, (20,20))

    if len(rects) == 0:
        return [], img
    rects[:, 2:] += rects[:, :2]
    return rects, img

def box(rects, img):
    for x1, y1, x2, y2 in rects:
        cv2.rectangle(img, (x1, y1), (x2, y2), (127, 255, 0), 2)
    cv2.imwrite('/vagrant/img/detected.jpg', img);

rects, img = detect("/vagrant/img/one.jpg")
box(rects, img)

The original image:

With faces detected