Mine

from Tkinter import *
import Image
import ImageTk
 
fen=Tk()
can=Canvas(fen,width=100,height=100,bg='ivory')
can.pack()
 
def change_image_2():
    global image2
    im = Image.open("ledverdeonoff.gif")
    im.seek(0)
    image2=ImageTk.PhotoImage(im)
    can.delete(ALL)
    can.create_image(50,50,image =image2)
    can.after(1800,change_image_1)
 
def change_image_1():
    global image1
    im = Image.open("ledverdeonoff.gif")
    im.seek(1)
    image1=ImageTk.PhotoImage(im)
    can.delete(ALL)
    can.create_image(50,50,image =image1)
    can.after(1800,change_image_2)
 
 
can.after(1800,change_image_1)
fen.mainloop()