#!/usr/bin/env python

# convert -resize 512x already-square.jpeg inimg.foo
# python zord.py inimg.foo > outimg.png 

import Image, sys

side = 9 # bits in an img side, e.g. 9 = 515*512

def dtob(n, l): # decimal (well, int type) to binary string
	r = ''
	for p in range(l):
		if n % 2 == 0:
			r = '0' + r
		else:
			r = '1' + r
		n >>= 1
	return r

def btod(b): # binary to 'decimal' int type
	return int(b, 2)

def inter(a, b, l): # interleave bit strings
	r = ''
	for p in range(l):
		r += a[p] + b[p]
	return r

def uninter(ab, l): # uninterleave bit strings
	# fix: len(a) and len(b) are necessarily len(ab)/2 --
	# passing length argument is dumb
	a, b = '', ''
	for p in range(l):
		a += ab[2*p]
		b += ab[2*p+1]
	return a, b

def xytoz(x, y): # z-order int to x,y coords
	return inter(dtob(x, side), dtob(y, side))

def ztoxy(z): # x,y coords to z-order int
	x, y = uninter(dtob(z, side*2), side)
	return btod(x), btod(y)

plain = Image.open(sys.argv[1]).load()
outf = Image.new('RGB', (2**side, 2**side))
out = outf.load()
for y in range(2**side):
	for x in range(2**side):
		target = ztoxy(y*(2**side) + x)
		out[x, y] = plain[target[0], target[1]]
outf.save(sys.stdout, "PNG")