Try to find the secret hidden inside this image.

enter image description here

Discovering one part of the secret may lead you to the starting point of another part. And so on.

It may look like an endless loop ...


... or is it?

Hint 2: that's the only hint needed for this puzzle.

  • $\begingroup$ This is very cool! $\endgroup$ Commented Jan 10, 2022 at 0:35

2 Answers 2


If we

shift the image 64 pixels and XOR it with itself... MOD 17
The clear message "MOD 17" appears.


look at the pixel values mod 17. Since they're all grayscale, all three values are the same, and so this sorts them into 17 groups. Making a new grayscale image (0 = black, 16 = white) produces this:


You may notice two things: (1) Some of the pixels are colored. The colored pixels are the odd results modulo 17.
(2) There are some patches of unmodified pixels. These are slightly off-grayscale.

Oh right, and we're being directed to another image.

Part 2

Another stereogram...

MOD 15
...and it says MOD 15 this time. Well, rinse and repeat.

einstein 2
So we're being redirected to... puzzle 114365, which is this very question. Huh.

Part 3

Now we have three characters from the first image, and two from the second; their spacing suggests that we interleave them.

This leads us to https://i.sstatic.net/5MahY.png, which tells us that it is the end of the puzzle.

end of puzzle
(Incidentally, the background image here is Lenna, another well-known image.)

  • $\begingroup$ Well done. You revealed about 2/3 of all secrets in this answer, and already reached the official end. Please keep further secrets secret (: $\endgroup$
    – WhatsUp
    Commented Jan 8, 2022 at 17:21
  • $\begingroup$ In part 2, "another" looks identical to the image in part 1, not with a different value. $\endgroup$ Commented May 26, 2022 at 2:42

LB Lenna to:

From Lenna to

Overlay both images in "difference" mode and you get "Congratulations! You have found the ultimate secret of this puzzle"


  • $\begingroup$ I don't see anything in the right half of the second spoiler's picture - did image compression do something? What should I be looking for? $\endgroup$
    – bobble
    Commented May 26, 2022 at 0:48
  • $\begingroup$ Nice answer, going beyond the official end! I'll set up a bounty to reward this answer. @bobble The pixels are very subtle. Some screens cannot display them properly. You need either a good monitor/screen or an image editor to scale them up a little. $\endgroup$
    – WhatsUp
    Commented May 27, 2022 at 9:31
  • $\begingroup$ Brightness and contrast all the way up: spoiler $\endgroup$
    – caPNCApn
    Commented May 27, 2022 at 20:27

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