Is it theoretically possible to have a hash function compatible with a resizing algo? For instance, if the resizer agreed to keep every N pixels intact, and the hash function only hashes those particular pixels? Likely N would have to be large enough to make it difficult to create a fake replacement image. Maybe every fourth pixel, which would be compatible with image resizing to 50% or 25% directly. Or every pixel in the center square of the image?

But really, I still don't understand the problem with #[7] method.

Don't mind me, I'm drinking.