Python - Tkinter cambio de imagen por otra

from tkinter import *

from tkinter import ttk

import sqlite3

import tkinter as tk

from tkinter import messagebox

import os

import configparser

import tkinter

from PIL import Image, ImageTk

from tkinter import filedialog

from PIL import ImageTk, Image

import tkinter

Product = Tk()

Product.title ('App - Add Product')

Product.iconbitmap(r'./local/pics/xCollectibles.ico')

# #SHOW IMAGE IN FRAME

def openfn():

    filename = filedialog.askopenfilename(title='App - Select a pic')

    return filename

def open_img():

    global img

    x = openfn()

    img = Image.open(x)

    img = img.resize((100, 100), Image.ANTIALIAS)

    img = ImageTk.PhotoImage(img)

    label2 = Label(frame, image=img).pack()

# #SHOW IMAGE IN FRAME

def save_image():

    print(image_names)

#FRAME PRODUCT

frame = LabelFrame (Product, text = 'Product Name')

frame.pack(anchor=NW)

label = Label (frame, text = 'Product:').pack(anchor=N)

name = ttk.Entry(frame).pack(anchor=N)

label1 = Label (frame, text = 'Pic:').pack(anchor=N)

# ###OPEN DEFAULT IMAGE

stim_filename = "./local/pics/none.png"

PIL_image = Image.open(stim_filename)

width = 100

height = 100

use_resize = False

if use_resize:

    PIL_image_small = PIL_image.resize((width,height), Image.ANTIALIAS)

else:

    PIL_image_small = PIL_image

    PIL_image_small.thumbnail((width,height), Image.ANTIALIAS)

img = ImageTk.PhotoImage(PIL_image_small)

label2 = Label(frame, image = img)

label2.image = img # keep a reference!

label2.pack()

###OPEN DEFAULT IMAGE

btn = Button (frame, text = 'Add Pic', command=open_img).pack(anchor=S)

# #FRAME PRODUCT

# #FRAME INFO

# frame1 = LabelFrame (Product, text = 'Info Maker')

# frame1.grid (row = 0, column =  1, sticky=NW)

# Label (frame1, text = 'Product:').grid (row = 1, column = 0)

# name = ttk.Entry(frame1)

# name.grid (row = 2, column = 0)

# #FRAME INFO

btn_save = Button (Product, text = 'save', command=save_image).pack(side=BOTTOM, anchor=W)

Product.mainloop()

def open_img():

    global img

    x = openfn()

    img = Image.open(x)

    img = img.resize((100, 100), Image.ANTIALIAS)

    img = ImageTk.PhotoImage(img)

    label2.config(image=img) #ésta línea reemplaza la tuya