I want to build face recognition with python, i follow the tutorial at youtube and then this error appear when i try to run the app.

I exactly follow the tutorial right, but i don’t know if i miss some of library installation.

So this is the code that i write :

import tkinter as tk
import cv2
from PIL import Image, ImageTk

import util

class App:
    def __init__(self):
        self.main_window = tk.Tk()
        self.main_window.geometry("1000x500+350+100")

        self.login_button_main_window = util.get_button(self.main_window, "Login", "green", self.login)
        self.login_button_main_window.place(x=640, y=300)
        self.register_new_user_button_main_window = util.get_button(self.main_window, "Register New User", "gray", self.register_new_user, fg='black')
        self.register_new_user_button_main_window.place(x=640, y=400)

        self.webcam_label = util.get_img_label(self.main_window)
        self.webcam_label.place(x=10, y=0, width=700, height=500)

        self.add_webcam(self.webcam_label)

    def add_webcam(self, label):
        **if 'cap' not in self.__dict__:
        self.cap = cv2.VideoCapture(0)**

        self._label = label
        self.process_webcam()

    def process_webcam(self):
        ret, frame = self.cap.read()
        self.most_recent_capture_arr = frame

        img_ =  cv2.cvtColor(self.most_recent_capture_arr, cv2.COLOR_BGR2RGB)
        self.most_recent_capture_pil Image.fromarray(img_)

        imgtk = ImageTk.PhotoImage(image=self.most_recent_capture_pil)

        self._label.imgtk = imgtk
        self._label.configure(image=imgtk)

        self._label.after(20, self.process_webcam)


    def login(self):
        pass

    def register_new_user(self):
        pass

    def start(self):
        self.main_window.mainloop()


if __name__ == "__main__":
    app = App()
    app.start()

And the error is :

 self.cap = cv2.VideoCapture(0)
    ^
IndentationError: expected an indented block after 'if' statement on line 23

Can someone help me with this problem? because i search for an hour but find nothing.

Fix my face recognition app