In my script, I try to capture the camera frame of my Surface device. It mostly works fine, but when I turn off my monitor using the power button, the light of the camera turns off. After that, even when I hold my finger over the camera, it still recognizes my face. I’ve tried resetting the frame, but it didn’t help. What am I doing wrong?

# -*- coding: utf-8 -*-

from tkinter import Tk
import sys, threading, os, face_recognition, time, keyboard, cv2, numpy as np, tkinter as tk

class Window:
    def __init__(self) -> None:
        self.win = Tk()
        self.win.attributes("-fullscreen", True)
        self.win.overrideredirect(True)

        self.label = tk.Label(self.win, text="Keinen Zugriff auf dieses Gerät!")
        self.label.config(font=("Segoe UI", 32, "bold"))
        self.label.place(relx=0.5, rely=0.5, anchor="center")

        self.label2 = tk.Label(self.win, text="Kamera wird initialisiert...")
        self.label2.place(relx=0.5, rely=0.6, anchor="center")
    
    def hide(self):
        self.win.withdraw()
    
    def show(self):
        self.win.deiconify()
    
    def set_debug(self, text):
        self.label2.config(text=text)

class App:
    def __init__(self):
        self.cam = None
        self.window = Window()
        
        threading.Thread(target=self.close_keys, daemon=True).start()
        threading.Thread(target=self.cam_reload, daemon=True).start()
        threading.Thread(target=self.face_rec, daemon=True).start()
        
        self.window.win.mainloop()
    
    def cam_reload(self):
        while True:
            if self.cam is None:
                self.cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)
                if self.cam.isOpened():
                    self.window.set_debug(text="")
                else:
                    self.cam.release()
                    self.cam = None
            time.sleep(1)
            print(self.cam)


    def close_keys(self):
        while True:
            if keyboard.is_pressed("alt") and keyboard.is_pressed("n") and keyboard.is_pressed("i") and keyboard.is_pressed("a"):
                os._exit(0)  
    
    def face_rec(self):
        path = "C:/Users/gemei/OneDrive/Desktop/Python/Security/images/Wolf.jpg"
        img = face_recognition.load_image_file(path)
        img_encodings = face_recognition.face_encodings(img)
        
        if not img_encodings:
            print("No face encodings found in the image.")
            return
        
        img_encoding = img_encodings[0]
        known = [img_encoding]
        known_names = ["admin"]

        while True:
            if not self.cam:
                self.cam = cv2.VideoCapture(0, cv2.CAP_DSHOW)
            
            if self.cam and self.cam.isOpened():
                ret, self.frame = self.cam.read()
                if ret:
                    print("Frame received")
                    small_frame = cv2.resize(self.frame, (0, 0), fx=0.25, fy=0.25)
                    rgb_small_frame = np.ascontiguousarray(small_frame[:, :, ::-1])

                    face_locations = face_recognition.face_locations(rgb_small_frame)
                    face_encodings = face_recognition.face_encodings(rgb_small_frame, face_locations)

                    for face_encoding in face_encodings:
                        matches = face_recognition.compare_faces(known, face_encoding)
                        name = "Unknown"
                        
                        if True in matches:
                            best_match_index = np.argmin(face_recognition.face_distance(known, face_encoding))
                            if matches[best_match_index]:
                                name = known_names[best_match_index]
                                self.face_detected = True
                                print("Face detected")

                    if self.face_detected:
                        self.window.hide()
                    else:
                        self.window.show()
                else:
                    print("No frame received")
                self.frame = None
                self.face_detected = False
                print(self.face_detected)

                

if __name__ == "__main__":
    while True:
        try:
            App()
        except:
            continue

I suspect it might have something to do with the threads I’m using.

self.frame = None

This is what i tried but it still saves the frame.