Need tkinter help with clicking buttons

[pythonprogrammer]

In the code below I have images of 3 dice (1,2,3) randomly selected and I have the on_click method in place to change the background to red for that die whenever the button for that die is clicked. However, I also want to print the value of that die when it is clicked. For example if 2 is clicked I want to print 2. What is happening when I click on one die it prints the value of all 3 dice randomly selected. So if the 3 random dice selected were 2,3,1 and I click on 2 it prints [[2], [3], [1]] instead of just 2. What do I need to change in my on_click method to fix this?

import random
from tkinter import *
from PIL import ImageTk, Image
import tkinter as tk
from tkinter import messagebox
from tkinter import simpledialog
from tkinter.messagebox import showinfo

root = Tk()


def on_click(event):
    event.widget.config(bg='red')

    buttons = [btn1, btn2, btn3]

    diceclicked = []
    for b in buttons:
        diceclicked.append([value for (key, value) in r.items() if b.cget('image') == key])
    print(diceclicked)

global dice1
dice1 = ImageTk.PhotoImage(Image.open("C:\\Users\\Dan\\Desktop\\Alea_1.png"))

global dice2
dice2 = ImageTk.PhotoImage(Image.open("C:\\Users\\Dan\\Desktop\\Alea_2.png"))

global dice3
dice3 = ImageTk.PhotoImage(Image.open("C:\\Users\\Dan\\Desktop\\Alea_3.png"))


r = {'pyimage1':1,'pyimage2':2,'pyimage3':3}

dice = [dice1,dice2,dice3]

rdice = random.choice(dice)
rdice2 = random.choice(dice)
rdice3 = random.choice(dice)


btn1 = Button(root, image=rdice)
btn1.pack()
btn1.bind('<Button-1>', on_click)

btn2 = Button(root,image=rdice2)
btn2.pack()
btn2.bind('<Button-1>', on_click)

btn3 = Button(root,image=rdice3)
btn3.pack()
btn3.bind('<Button-1>',on_click)

root.mainloop()