Provided you know the exact method you can in theory recover even the edges. Although this is very numerically unstable, to the extent that just double precisio

Provided you know the exact method you can in theory recover even the edges. Although this is very numerically unstable, to the extent that just double precision might not be quite enough. That said, that's just the theoretical exact inverse. With proper regularization you might be able to recover far more (although with a complex prior like a neural network it becomes debatable what information you are recovering and what information you are putting in yourself). Side note, even with a mere 25px image (effectively) of someone's face I'm not sure if it leaks as little information as you think it does. Just 33 bits would be enough to uniquely identify someone, let alone 75 bytes. Practically you wouldn't be able to recover more than some basic estimates of skin colour and distance between the eyes etc, but in extreme cases that might still too much.