Python Prime Number Viewer

image.py

from PIL import Image

height = 1039
width = 1039
im = Image.new("RGB", (width,height), "white")

pixels = im.load()
f = open('prime_colors', 'r')

for x in range(width):
  for y in range(height):
    colors = f.readline()
    if len(colors) == 0:
        break
    colors = colors.split(',')
    pixels[x,y] = (int(colors[0]), int(colors[1]), int(colors[2]))

im.save("primes.png")

primes.py

def primes_sieve1(limit):
    limitn = limit+1
    primes = dict()
    for i in range(2, limitn): primes[i] = True

    for i in primes:
        factors = range(i,limitn, i)
        for f in factors[1:]:
            primes[f] = False
    return [i for i in primes if primes[i]==True]

def convert_to_base_256(n):
    if n > 256**3:
        print("number is too large: " + str(n))
    squared = n // (256**2)
    base    = n // 256 % 256
    single  = n % 256
    return [squared, base, single]

if __name__ == "__main__":
    primes = primes_sieve1(256**3)
    for i in primes:
        base256 = convert_to_base_256(i)
        print("(" + str(base256[0])+"," +  str(base256[1])+ "," + str(base256[2]) + ")")