Simple application in Python using OpenCV for face

Question

I have been working on a simple Python application for face recognition with OpenCV. My code does its work and gets the job done, but I'm wondering if there's a 'better' way to do this. I hope I can get some tips on how to structure or approach this task.

See my full code 1 and 2.

while True:
 (_, im) = webcam.read()
 gray = cv2.cvtColor(im, cv2.COLOR_BGR2GRAY)
 persons = face_cascade.detectMultiScale(gray, 1.3, 5)
 for (x,y,w,h) in persons:
 cv2.rectangle(im,(x,y),(x + w,y + h),(0, 255, 255),2)
 face = gray[y:y + h, x:x + w]
 rescaling_the_face = cv2.resize(face, (width, height))
 prophecy = model.predict(rescaling_the_face)
 cv2.rectangle(im, (x, y), (x + w, y + h), (0, 255, 255), 2)
 if prophecy[1]<400:
 cv2.putText(im,'%s' % (names[prophecy[0]]),(x + 10, (y + 22) + h), cv2.FONT_HERSHEY_PLAIN,1.5,(20,205,20), 2)
 else:
 cv2.putText(im,'STRANGE_PERSON',(x + 10, (y + 22) + h), cv2.FONT_HERSHEY_PLAIN,1.5,(65,65, 255), 2)
 cv2.imshow('OpenCV Face Recognition - esc to close', im)
 key = cv2.waitKey(10)
if key == 27:

Answer 1

Some notes only:

Instead of

(_, im) = webcam.read()

is more common not to use parentheses:

_, im = webcam.read()

(and similarly in other places of your code).

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Too many blank lines. In the PEP 8 - Style Guide for Python Code repeatedly occurs the word "sparingly" for the Blank Lines usage.

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(Correcting English only):

Instead of

print("Webcam is open? ", webcam.isOpened())

use

print("Is the webcam open? ", webcam.isOpened())

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Magic numbers in your code, as in this statement

if key == 27:

Why not use names for such constants, e. g.

ESC_KEY = 27 # Near the start of your code
...
...
if key == ESC_KEY: