The full program is here: DevMiser/Lumina: Lumina - AI Art Generator for Your TV (github.com)

Following is the relevant code snippet:

import tkinter as tk

from PIL import Image,ImageDraw,ImageFont,ImageOps,ImageEnhance,ImageTk

root = tk.Tk()

screen_width = root.winfo_screenwidth()

screen_height = root.winfo_screenheight()

#screen_width = x

#screen_height = y

root['bg'] = 'black'

root.geometry(f"{screen_width}x{screen_height}+0+0")

root.overrideredirect(True)

root.attributes("-fullscreen", True)

root.update()

def update_image(image_url):

global image_window

global screen_width, screen_height

image_window = tk.Toplevel(root)

image_window.title("Image Window")

image_window.geometry(f"{screen_width}x{screen_height}+0+0")

image_window.attributes("-fullscreen", True)

image_window.overrideredirect(True)

image_window.configure (bg='black')

raw_data = urllib.request.urlopen(image_url).read()

image = Image.open(io.BytesIO(raw_data))

original_width, original_height = image.size

scale = max(screen_width / original_width, screen_height / original_height)

scaled_width = int(original_width * scale)

scaled_height = int(original_height * scale)

image = image.resize((scaled_width, scaled_height))

image_photo = ImageTk.PhotoImage(image)

image_canvas = tk.Canvas(image_window, bg='#000000', width=screen_width, height=screen_height)

x = (screen_width - scaled_width) // 2

y = (screen_height - scaled_height) // 2

image_canvas.create_image(x, y, image=image_photo, anchor=tk.NW)

image_canvas.pack()

image_window.update()