solution.py

# -*- coding: utf-8 -*-
import sys
from PIL import Image
from nums2 import _f, _g
import struct

im = Image.open(sys.argv[1])
rgb_im = im.convert('RGB')
widht, height = im.size#(1664,1248)
#data = open(sys.argv[1],'rb').read()[0x36:]
res = []
print (widht, height)

for i in range(widht):
	for j in range(height):
		r, g, b = rgb_im.getpixel((i,j))
		bits_r = r & 7 #3 bits
		bits_g = g & 7 #3 bits
		bits_b = b & 3 #2 bits
		v = (bits_b << 6) + (bits_g << 3) + bits_r
		res.append(v)


with open('result.dat','wb') as f:
	f.write(bytearray(res))


rol = lambda val, r_bits, max_bits: \
	(val << r_bits%max_bits) & (2**max_bits-1) |  \
	((val & (2**max_bits-1)) >> (max_bits-(r_bits%max_bits)))
 
# Rotate right: 0b1001 --> 0b1100
ror = lambda val, r_bits, max_bits: \
	((val & (2**max_bits-1)) >> r_bits%max_bits) | \
	(val << (max_bits-(r_bits%max_bits)) & (2**max_bits-1))
 
max_bits = 8  # For fun, try 2, 17 or other arbitrary (positive!) values

txt = []
num2 = 0
num = 0
for i in range(len(res)):
	if i % 100000 == 0:
		print(i)

	k2, num2 = _g(num, num2)
	num += 1
	k1, num2 = _g(num, num2)
	num += 1

	txt.append((ror(rol(res[i], 3, 8) ^ k1, 7, 8) ^ k2))

with open('results.decoded', 'wb') as f:
	f.write(bytearray(txt))