# What is hidden on this image?

Here's the image: What is hidden on it and how was it made?

• Pixelation at its best. – Arthur Rey Mar 18 '15 at 13:05

## 3 Answers

I got it!

First attempt:

I separated the RGB channels, XOR'd them with each other, inverted them, and arbitrarily assigned the results R=~(R^G); G=~(R^B); B=~(G^B) based on what would make the hair and skin hue broadly correct.

Result image: The result isn't correct, but it made whatever component caused the moire patterns drop out.

EDIT: I got it!

The image is XOR'd with the function (x*y)%256.

Final image: Clean function: • I was thinking of giving a hint in form of classic x^y map eventually, but I thought it would be too much. Congratulations. – rr- Mar 18 '15 at 16:06

This is how far I got; I created a python script to create a background image that I substracted from the given image (Update): This is the Python script I used:

import sys
from PIL import Image
src = Image.open(sys.argv)
def tf(p,i,j):
return tuple([256-(x-(256-i*j)/64*64)%256 for x in p])
odata = [tf(src.getpixel((j,i)),i,j) for i in range(0,256) for j in range(0,256)]
img = Image.new('RGB', (256,256))
img.putdata(odata)
img.save('2.png')


So it's basically the same as the accepted answer, but there is some small error in there somewhere..

And this is the correct python script using XOR instead of difference:

import sys
from PIL import Image
src = Image.open(sys.argv)
def tf(p,i,j):
return tuple([(x^i*j)%256 for x in p])
odata = [tf(src.getpixel((j,i)),i,j) for i in range(0,256) for j in range(0,256)]
img = Image.new('RGB', (256,256))
img.putdata(odata)
img.save('3.png')

• Looks like Ayanami Rei from Neon Genesis Evangelion – JonTheMon Mar 18 '15 at 13:03
• That's exactly who it is. – generalcrispy Mar 18 '15 at 13:11
• You're very close, it's Rei indeed. The image can be recovered with zero artifacts, though, using a very simple transformation. – rr- Mar 18 '15 at 13:13
• Out of curiosity, what are the details of your solution? – Random832 Mar 18 '15 at 19:33

There is someone hidden in the image. I put the image here and got this: • Unfortunately, that's too vague. It wouldn't be interesting if you could see it through Magic Eye :P – rr- Mar 18 '15 at 11:53
• I can do magic eye puzzles, if I tried it with this image my eyes would fall out... – Bobby Mar 18 '15 at 14:59