Hackvent_2018/Day 8/decode.py

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2018-12-08 19:27:34 +01:00
#!/usr/bin/python
from PIL import Image
import types
im = Image.open("4dv3ntSn4il_cropped.png")
pix = im.load()
numTiles = 25
tileSize = im.size[0] // numTiles
data = [["0" for x in range(numTiles)] for y in range(numTiles)]
for x in range(0, numTiles):
for y in range(0, numTiles):
x_abs = x*tileSize + tileSize // 2
y_abs = y*tileSize + tileSize // 2
pixel = pix[x_abs, y_abs]
if type(pixel) is tuple:
data[x][y] = "0" if pixel == (255,255,255) else "1"
else:
data[x][y] = "0" if pixel / 255 > 0.5 else "1"
bits = ''.join([''.join([data[x][y] for x in range(numTiles)]) for y in range(numTiles)])
print("Number of Zeros:", bits.count("0"), "Number of Ones:", bits.count("1"), "Length:", len(bits))
snail = ""
clockwise = False
bounds = [[0,numTiles-1],[0, numTiles-1]]
pos = [0,0]
dir = [1,0] if clockwise else [0, 1]
pixels = []
while len(snail) < numTiles*numTiles:
if pos in pixels:
print("Fault:", pos, "already processed")
pixels.append(pos)
snail += data[pos[0]][pos[1]]
next_pos = [pos[0] + dir[0], pos[1] + dir[1]]
if dir[0] == 1 and next_pos[0] > bounds[0][1] or dir[0] == -1 and next_pos[0] < bounds[0][0] or dir[1] == 1 and next_pos[1] > bounds[1][1] or dir[1] == -1 and next_pos[1] < bounds[1][0]:
if clockwise:
if dir[0] == 1:
dir = [0, 1]
bounds[0][1] -= 1
elif dir[0] == -1:
dir = [0, -1]
bounds[0][0] += 1
elif dir[1] == 1:
dir = [-1, 0]
bounds[1][1] -= 1
elif dir[1] == -1:
dir = [1, 0]
bounds[1][0] += 1
else:
if dir[0] == 1:
dir = [0, -1]
bounds[1][1] -= 1
elif dir[0] == -1:
dir = [0, 1]
bounds[0][1] -= 1
elif dir[1] == 1:
dir = [1, 0]
bounds[0][0] += 1
elif dir[1] == -1:
dir = [-1, 0]
bounds[1][0] += 1
next_pos = [pos[0] + dir[0], pos[1] + dir[1]]
pos = next_pos
if snail.count("0") != bits.count("0") or snail.count("1") != bits.count("1"):
print("Bits do not match")
exit()
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im = Image.new('RGB', im.black)
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pix = im.load()
for tileY in range(0, numTiles):
for tileX in range(0, numTiles):
bit = snail[tileX * numTiles + tileY]
for x in range(0, tileSize):
for y in range(0, tileSize):
x_abs = tileX * tileSize + x
y_abs = tileY * tileSize + y
pix[x_abs,y_abs] = (0,0,0,255) if bit == "1" else (255,255,255,255)
im.save("decoded.png")