0. Reverse image search to find out it's hilbert + peano -> [hilbert curves](https://en.wikipedia.org/wiki/Hilbert_curve)
1. Generate hilbert curve of order 9, 2 (2^9 = 512, 2 = 2d)
2. iterate image in hilbertCurve.transpoed order
3. LSB of B bits
4. PNG file

```
from BitVector import BitVector
from PIL import Image
from hilbertcurve.hilbertcurve import HilbertCurve
import math

img = Image.open("stego.png")

# build a list of hilbert curve coordinates
hc = HilbertCurve(int(math.log2(img.height)), 2)
locations = [hc.coordinates_from_distance(i) for i in range(hc.max_h+1)]

# iterate the pixels in transposed hilbert curve order
bitlist = [img.getpixel((y,x))[2] & 1 for (x,y) in locations]
BitVector(bitlist=bitlist).write_to_file(open("out.png", "wb"))

Image.open("out.png")
```