Color in red diffrencies between two pictures

Color in red diffrencies between two pictures

I'm a beginner in python and i have some difficulties to do what i want to
do.
I want to spot the difference between two images in a game "spot seven
diffenrecies".
from PIL import Image
from PIL import ImageChops
a = Image.open("pict1.jpg")
b = Image.open("pict2.jpg")
diff = ImageChops.difference (a, b)
Now i want to enlight in red the differences like that:
http://imgur.com/mvfJs3z
http://imgur.com/lCZn7PY
Can you help me (and my awesome english) ? :D