What are the additional modules for?

Question

Python

I am writing a script for my needs that recognizes faces in a photo and saves a fragment of a photo with a face in a subdirectory. When looking for ready-made solutions, I came across this code:

import numpy as np
import cv2
from matplotlib import pyplot as plt

face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
eye_cascade = cv2.CascadeClassifier('haarcascade_eye.xml')

img = cv2.imread('xfiles4.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

faces = face_cascade.detectMultiScale(gray, 1.3, 5)


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)

cv2.imshow('img',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

And I don’t understand why matplotlib and numpy are needed here if they are not used anymore in the code?

Answer 1

Good afternoon.
When I am tormented by a question about a module I do not know, I go off. documentation.
Then I return to the code and start tracing, already ~ understanding what is happening, for a deeper understanding, you need to 'intimately' get acquainted with the functions of this module.