I had to import the PIL.ImageTk module separately. The line of code
import PIL
did not import the PIL.ImageTk module and I had to additionally use
from PIL import ImageTk
and then it worked fine in the Enthought Canopy 1.0 distribution of Python 2.7.
The need for that solution was suggested by this redhat bug resolution:https://bugzilla.redhat.com/show_bug.cgi?id=247171
This could also be accomplished with import PIL.ImageTk.