Related work (all involve noise and flickering images, photosensitive eyes/brains beware):

- "This game disappears if you pause it": https://youtu.be/Bg3RAI8uyVw

- "Illusion: If You Pause, The Image Will Disappear": https://youtu.be/ZqGfb_Vlrig

I see tons of confustion in the comments on whether AI can or can't read it. Bit of a marketing miss -- they should have picked clearly different decoy vs. default actual messages.

can't you use font shaping rules or whatever it is to essentially begin a span of text with a "private key" that then causes the rest of the message to render correctly by combining with it (a trivial version could be e.g. a rot-N based on a given N)

Claude Opus 4.8 can read it with a single prompt and no instructions on how to read it.

https://ibb.co/WWMSXQkQ

Technically it's not a font, because font needs to be still. Analogy: if I took photo after book was closed would we say that font cannot be read by a camera?

Took a picture (only a single frame) and a 1s movie and threw it toward GPT 5.6 Sol (High):

Frame took 9m30s to decyper and GPT 5.6, it returned: WRITTEN IN GHOST FONT. Weird because I can only see "GHOST FONT" on the demo... but extracted data from image (I saw the highlited one) definitely looks like the "Ghost Font".

--

Video is more amusing, because after 3m GPT 5.6 figured it's motion-defined and asked to run QuickTime. At one moment I got:

> The animation is a motion-defined illusion. I’ve confirmed there’s no readable static OCR layer; I’m decoding its optical-flow field so the letter shapes become explicit.

At 4m it got extracted motion image that was in shape of letters but analyzed for 9 more letters and returned (at 13m36s) "GHOST FONT"

--

So:

    a font...             - FALSE - not a font, but video effect
    ...humans can read... - FALSE - I can't read it from image (but AI can!)
    ...but AI cannot      - FALSE - it can

:D

Edit: https://imgur.com/a/SHlGu4O - work-in-progress images

See also: a "font" that only people high on drugs can read!

https://qri.org/blog/psycrypto-contest

https://www.youtube.com/watch?v=oD4nV0CMkBI

Of course, the psychedelic hidden message is reversible with some video processing techniques for everyone else to see. And calling it cryptography is a mis-use of the term. Still an interesting use of the effect.

I don't think "ghost font" will work as well as the author claims.

When I gave Fable a screenshot it found the GHOST portion of GHOST FONT. Based on pixel density via some python code apparently - https://imgur.com/a/m3c801F

I had thought to use homographs. Sadly, all the models I tried were able to decode something like:

"ﾌㄖ乇ㄚ ᗪㄖ乇丂几'ㄒ 丂卄卂尺乇 千ㄖㄖᗪ"

However, I have noticed that voice assistants have a hard time understanding homonyms. Saying "bow" (as in to bow one's head) is often stored as "bow" (as in a bow and arrow). I wonder if there's a sufficiently complex sentence which is intelligible to humans but not to machines?

I haven’t tried, but it looks like you could trivially solve with optical flow?

Edit: looks like yes, from the shared chats people are posting. But it’s interesting to think of communication schemes that require a temporal component so any single image is unreadable and can’t be beaten by long exposures or other tricks (otherwise persistence of vision displays would satisfy). A sort of physical anti copy/paste.