[mapontosevenths]

I'm not even sure what you're hypothetically describing here. You want a system that authenticates that an image hasn't been manipulated, but which still allows you to compress and transcode it? It's feasible in the same way that synthid was feasible, but I don't think there's actually a use case for it. You either want it to be unedited or you don't. I'm not sure how you can say "edited, but only exactly this much editing is allowed."

I suppose the validator could do a fuzzy match and just output a similarity score that compares the result to the original image. IE - This image is 75% similar to the original with something like a perceptual hash. Then it's the users problem to decide if 75% is close enough for their trust.

[Ajedi32]

> You either want it to be unedited or you don't.

You want it visually identical but not necessarily bit-for-bit identical. Compression and transcoding should not cause validation to fail unless the compression artifacts are particularly severe, but even a tiny, one-pixel change that substantially alters the appearance of the photo should cause validation to fail.

And yes I agree this is hard to quantify and impossible with existing algorithms, that was my point.