Detect human face with live feeds from Webcam.

You will need,

 PyCharm IDE 2018.2

 OpenCV-python 3.2.0.8

 Python 3.6

import can load the modules into the current namespace so that you can access the functions and anything else defined within the module using the module name.

import cv2
import sys

cv2 OpenCV-Python is a library of Python bindings designed to solve computer vision problems.
sys provides access to some variables used or maintained by the interpreter and to functions that interact strongly with the interpreter.

haarcascade is basically a classifier which is used to detect the object for which it has been trained for, from the source.

cascPath = "haarcascade_frontalface_default.xml"
faceCascade = cv2.CascadeClassifier(cascPath)

haarcascade_frontalface_default.xml is a haar cascade designed by OpenCV to detect the frontal face.

define a video capture object

video_capture = cv2.VideoCapture(0)

0 is for default camera.

capturing frame by frame

ret, frame = video_capture.read()

Covert frames to gray scale

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

Detecting face

faces = faceCascade.detectMultiScale(
        gray,   
        scaleFactor=1.1,    
        minNeighbors=5,     
        minSize=(30, 30),   
        flags=cv2.CASCADE_SCALE_IMAGE
    )

faces = faceCascade.detectMultiScaledetecting related object
gray, gray scale
scaleFactor=1.1, scale the face
minNeighbors=5, number of objects
minSize=(30, 30), window size

Drawing the rectangle around the detacted face.

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

Displaying the results

cv2.imshow('Video', frame)

Adding command to stop running the program

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

waiting to q key to pressed to exit.

When everything is done, release the capture

video_capture.release()
cv2.destroyAllWindows()