count faces with python and opencv

Question

I have script in python using opencv2 to detect face. I take video in my webcam and using Haar Cascade for detect faces. I want to get out of the number of detected faces in a one frame. I understand that this can be done by counting rectangles when a face is found. how to do it? How to count rectangles in one frame?

import cv2
import sys

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

video_capture = cv2.VideoCapture(0)


while True:
    # Capture frame-by-frame
    ret, frame = video_capture.read()

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

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

    # Draw a rectangle around the faces
    for (x, y, w, h) in faces:
        cv2.rectangle(frame, (x, y), (x+w, y+h), (0, 255, 0), 2)



    # Display the resulting frame
    cv2.imshow('Video', frame)


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

# When everything is done, release the capture
video_capture.release()
cv2.destroyAllWindows()

Answer 1

Simple use of len(faces) should return the number of faces.