Hackvent_2019/Day 09/decode.py
2019-12-09 15:09:46 +01:00

95 lines
2.2 KiB
Python

#!/usr/bin/python
from PIL import Image
import numpy
im = Image.open("qr.png")
input = im.load()
# QR Version 4
size = 33
pixelSize = im.size[0] // size
# rule 30
codes = {
"111": 0,
"110": 0,
"101": 0,
"100": 1,
"011": 1,
"010": 1,
"001": 1,
"000": 0
}
def translatePos(pos):
x = pos[0] * pixelSize + pixelSize // 2
y = pos[1] * pixelSize + pixelSize // 2
return (x, y)
def fillPixel(pos, bit, pix):
color = (0,0,0) if bit == 1 else (255,255,255)
for x in range(5):
for y in range(5):
pix[pos[0]*pixelSize+x,pos[1]*pixelSize+y] = color
def readPos(pos, pix, size):
if pos[0] < 0 or pos[0] >= size[0] or pos[1] < 0 or pos[1] >= size[1]:
return 0
translated = translatePos(pos)
return 0 if pix[translated] == 255 else 1
def readBufPos(pos, buf):
x = pos[0]
y = pos[1]
if x < 0 or x >= buf.shape[0] or y < 0 or y >= buf.shape[1]:
return 0
return int(buf[x,y])
def rule30decode(x, y, buf):
bits = "".join([str(readBufPos(p, buf)) for p in [(x - 1, y - 1), (x, y - 1), (x + 1, y - 1)]])
return codes[bits]
# Used to save rule30 pyramid for visualization
def bufToImage(buf, filename, pixelSize = 5):
imgSize = (buf.shape[0] * pixelSize, buf.shape[1] * pixelSize)
outImage = Image.new('RGB', imgSize, 255)
outPixel = outImage.load()
for x in range(0, buf.shape[0]):
for y in range(0, buf.shape[1]):
color = (0,0,0) if int(buf[x,y]) == 1 else (255,255,255)
for i in range(pixelSize):
for j in range(pixelSize):
outPixel[x*pixelSize+i,y*pixelSize+j] = color
outImage.save(filename)
# 33 + 33/2 + 2
bufSize = 51
buf = numpy.zeros(shape=(bufSize,bufSize))
buf[buf.shape[0]//2,0] = 1
for y in range(1,buf.shape[1]):
for x in range(0,buf.shape[0]):
buf[x,y] = rule30decode(x,y,buf)
# bufToImage(buf, "rule30.png")
offsetX = (bufSize-33)//2-1
offsetY = 0
outImage = Image.new('RGB', im.size, 255)
outPix = outImage.load()
for x in range(size):
for y in range(size):
bit1 = readPos((x,y), input, im.size)
bit2 = int(buf[offsetX+x,offsetY+y])
bit = bit1 ^ bit2
fillPixel((x,y), bit, outPix)
outImage.save("decoded.png")