What does HackerNews think of unredacter?

If it's so easy and already done why not show it actually reconstructing real examples like that page. The reality is there is no existing well known approach for recovering data in the exact way you laid out. Similar approaches sure but they rely on different data sources (such as downsampled versions of text) instead of artifacts. That it is feasible in the easy case does not mean it is feasible in the hard case, why should the two be expected to hold the exact same amount of information about the source? Even if they do the method of reconstruction will surely be different.

> I am just showing that jpg compression cast a digital shadow on itself that can be outside of the cropped area, which many people find unintuitive.

That I agree 100%, and it's a great thing to show, it's just a bit overreaching to then name that "jpguncrop" with a description referring to aCropalypse instead. Maybe it could lead to something like that but what's in the repository does not match the name or description.

> Matching the shape of this digital shadow (which is not very small (all the highlighted pixel region contain some info) ), combined with an educated prior on the missing portion (that must provide a way to represent the hidden portion in less bits than you can get from the shape of the shadow) , can help you recover the data.

Great, you have a theory - demonstrate! I'll be the first to comment on how clever, persevering, and well executed the work was if you post a thread showing it works. Until that point though it isn't so just because you think it would work.

Here is a great test case https://i.imgur.com/sAEpfQ6.jpg. The font size should be small enough that data leaks out of the obfuscated area from the characters. I'm optimistic this blind reconstruction case is feasible given the additional constraints compared to the circle test but it would probably take a decent chunk of new work.