#!/usr/bin/env python

import Image
import sys

MODE_4_IMAGE_W = 512
MODE_4_IMAGE_H = 256
MODE_8_IMAGE_W = 256
MODE_8_IMAGE_H = 256

def convert_mode_4(data):
	image = Image.new("RGB", (MODE_4_IMAGE_W, MODE_4_IMAGE_H))

	for y in range(MODE_4_IMAGE_H):
		for x in range(MODE_4_IMAGE_W):
			pixel = (y * MODE_4_IMAGE_W / 8) + (x / 8)
			index = pixel * 2
			bit = 7 - (x % 8)

			byte0 = ord(data[index])
			byte1 = ord(data[index + 1])

			if ((byte0 >> bit) & 1) != 0:
				g = 0xff
			else:
				g = 0

			if ((byte1 >> bit) & 1) != 0:
				r = 0xff
			else:
				r = 0

			b = 0

			rgb = (b << 16) | (g << 8) | r

			image.putpixel((x, y), rgb)

	return image

def convert_mode_8(data):
	image = Image.new("RGB", (MODE_8_IMAGE_W, MODE_8_IMAGE_H))

	for y in range(MODE_8_IMAGE_H):
		for x in range(MODE_8_IMAGE_W):
			pixel = y * (MODE_8_IMAGE_W / 4) + (x / 4)
			index = pixel * 2
			byte_pixel = (3 - (x % 4)) * 2

#			print "%i,%i -> index %i, %i" % (x, y, index, byte_pixel)

			r_bit = byte_pixel + 1
			g_bit = byte_pixel + 1
			b_bit = byte_pixel

			byte0 = ord(data[index])
			byte1 = ord(data[index + 1])

			if ((byte0 >> g_bit) & 1) != 0:
				g = 0xff
			else:
				g = 0

			if ((byte1 >> r_bit) & 1) != 0:
				r = 0xff
			else:
				r = 0

			if ((byte1 >> b_bit) & 1) != 0:
				b = 0xff
			else:
				b = 0

			rgb = (b << 16) | (g << 8) | r

			image.putpixel((x, y), rgb)

	return image

# Check command line

if len(sys.argv) < 3:
	print "Usage: %s <source> <dest>" % sys.argv[0]

# Read source data

f = file(sys.argv[1])

source_data = f.read(MODE_4_IMAGE_W * MODE_4_IMAGE_H / 2)

f.close()

# Convert image

image = convert_mode_4(source_data)

# Write output file

f = file(sys.argv[2], "w")

image.save(f, "png")

f.close()