tuple indices must be integers or slices, not str

[cybertooth]

I am trying to make a Tkinter GUI with PyMuPDF. however I am geting the error

Error:
Traceback (most recent call last):
  File "C:\Users\INDIAN\Desktop\python exercises\pygametooth\pdf2jpg2.py", line 21, in <module>
    image_ext = img['str']
TypeError: tuple indices must be integers or slices, not str

.
can some one help fix this.

import fitz
import tempfile
import os
import tkinter as tk
from PIL import Image, ImageTk

# create a temporary directory to store extracted images
temp_dir = tempfile.TemporaryDirectory()

# open PDF file
doc = fitz.open('G:\\Patient OPG\\Arshita Nagpal\\CBCT 48,38\\Axials.pdf')

# iterate over pages
for page_index in range(doc.page_count):
    # get the page
    page = doc[page_index]
    
    # iterate over images
    for image_index, img in enumerate(page.get_images()):
        # get the image extension
        image_ext = img['str']
                        
        # get the pixmap
        pixmap = page.get_pixmap(image_index)
        # get the image data
        image_data = pixmap.tobytes()
        # save the image to the temporary directory
        image_path = os.path.join(temp_dir.name, f"image{page_index+1}_{image_index}.{image_ext}")
        pixmap.save(image_path)
##        with open(image_path, 'wb') as f:
##            f.write(image_data)

# create a tkinter window
root = tk.Tk()

# iterate over extracted images and display them in the tkinter window
for image_file in os.listdir(temp_dir.name):
    image_path = os.path.join(temp_dir.name, image_file)
    # open image with PIL
    image = Image.open(image_path)
    # convert image to tkinter-compatible format
    photo = ImageTk.PhotoImage(image)
    # create a label with the image and add it to the tkinter window
    label = tk.Label(root, image=photo)
    label.pack()

# start the tkinter mainloop
root.mainloop()

# delete the temporary directory
temp_dir.cleanup()