My Background Image Is Not Appearing (Python Tkinter)

[HailyMary]

Hello, Can someone help me in Fixing the code below? I need to put image which is school.jpg as a background image in my Python GUI using Tkinter but apparently, it didn't appear. Only grey color was present in there. Thanks.

from tkinter import *
from PIL import ImageTk, Image


class Student:

    def __init__(self, root):
        # no resize for both directions
        height = 750
        width = 1230
        x = (root.winfo_screenwidth() // 2) - (width // 2)
        y = (root.winfo_screenheight() // 2) - (width // 2)
        self.root = root
        self.root.title("Image")
        self.root.geometry('{}x{}+{}+5'.format(width, height, x, y))
        self.root.config(bg="forestgreen")

        StdID = StringVar()
        Firstname = StringVar()
        Surname = StringVar()
        DoB = StringVar()
        Age = StringVar()
        Gender = StringVar()
        Address = StringVar()
        Mobile = StringVar()



        # Frame
        img = Image.open('images\\school.jpg')
        bg = ImageTk.PhotoImage(img)

        MainFrame = Label(self.root, image = bg)
        MainFrame.place(x=0, y=0)
        MainFrame.grid()


if __name__ == '__main__':

    root = Tk()

    application = Student(root)



    root.mainloop()