How it's works

1. First dowload library opencv and numpy

pip install opencv-python
pip install numpy

2. Make the program to connect to the webcam

import cv2
import numpy as np

cap = cv2.VideoCapture(0)
while True:
    _, frame = cap.read()
    cv2.imshow('just face', frame)
        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

cap.release()
cv2.destroyAllWindows()

3. Download the model for face, that is haarcascade_frontalface_default.xml
4. Write the code to translate the model

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

5. Load the image in grayscale

frame = cv2.imread('', cv2.IMREAD_GRAYSCALE)

By changing to gray, the program will be easier to learn

6. Turn the picture to gray color

gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

7. To make a rectangle, use this code

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

Demo

Clik the picture to see the Video