Alright, i had this homework recently (don't worry, i've already done it, but in c++) but I got curious how i could do it in python. The problem is about 2 light sources that emit light. I won't get into details tho.

Here's the code (that I've managed to optimize a bit in the latter part):

import math, array
import numpy as np
from PIL import Image

size = (800,800)
width, height = size

s1x = width * 1./8
s1y = height * 1./8
s2x = width * 7./8
s2y = height * 7./8

r,g,b = (255,255,255)
arr = np.zeros((width,height,3))
hy = math.hypot
print 'computing distances (%s by %s)'%size,
for i in xrange(width):
    if i%(width/10)==0:
        print i,    
    if i%20==0:
        print '.',
    for j in xrange(height):
        d1 = hy(i-s1x,j-s1y)
        d2 = hy(i-s2x,j-s2y)
        arr[i][j] = abs(d1-d2)
print ''

arr2 = np.zeros((width,height,3),dtype="uint8")        
for ld in [200,116,100,84,68,52,36,20,8,4,2]:
    print 'now computing image for ld = '+str(ld)
    arr2 *= 0
    arr2 += abs(arr%ld-ld/2)*(r,g,b)/(ld/2)
    print 'saving image...'
    ar2img = Image.fromarray(arr2)
    ar2img.save('ld'+str(ld).rjust(4,'0')+'.png')
    print 'saved as ld'+str(ld).rjust(4,'0')+'.png'

I have managed to optimize most of it, but there's still a huge performance gap in the part with the 2 for-s, and I can't seem to think of a way to bypass that using common array operations... I'm open to suggestions :D