Cycle through all 16 million possible RGB colors and display them in an image

allcolors.py

#!/usr/bin/env python

from PIL import Image
import itertools
import sys
import time

def gen_image():
    im = Image.new('RGB', (4096,4096))
    pix = im.load()
    g = itertools.product(range(256), repeat=3)
    for i in range(4096):
        for j in range(4096):
            pix[i,j] = g.next()
    return im

def timeit(func):
    start = time.time()
    result = func()
    end = time.time()
    print end - start, 's'
    return result

if __name__ == '__main__':
    im = timeit(gen_image)
    im.save(sys.argv[1])