PIL is now replaced by Pillow http://pillow.readthedocs.io/en/3.2.x/
solution:
from Tkinter import *
import PIL.Image
import PIL.ImageTk
root = Toplevel()
im = PIL.Image.open("photo.png")
photo = PIL.ImageTk.PhotoImage(im)
label = Label(root, image=photo)
label.image = photo # keep a reference!
label.pack()
root.mainloop()
If PIL
could not be found in code, you do need a pillow
install:
pip install pillow