naive_image_similarity.py

import Image
from numpy import average, linalg, dot
import sys

images = sys.argv[1:3]
vectors = []
norms = []

for image in images:
  vector = []
  
  for pixel_tuple in Image.open(image).getdata():
    vector.append(average(pixel_tuple))
  
  vectors.append(vector)
  norms.append(linalg.norm(vector, 2))

a, b = vectors
a_norm, b_norm = norms

print dot(a / a_norm, b / b_norm)