Indeed, trick is normal humans are not going to remember, let along recognize 256 bits of state from a picture. Seems like the best you can hope for is enough

Indeed, trick is normal humans are not going to remember, let along recognize 256 bits of state from a picture. Seems like the best you can hope for is enough bits in a fingerprint that users can tell when it changes and make it harder to find a fingerprint that fools the user.