And that's just in the non-adversarial simple case.

If you don't know the provenance of images you are putting black box on (for example because of a rogue employee intentionally wanting to leak them, or if the image sensor of your target had been compromised to leak some info by another team), your redaction can be rendered ineffective, as some images can be made uncroppable by construction .

(Self-plug : https://github.com/unrealwill/uncroppable )

And also be aware that compression is hiding everywhere : https://en.wikipedia.org/wiki/Compressed_sensing

Right, using stenography to encode some parity bits into an image so that lost information can be reconstructed seems like an obvious approach - all sorts of approaches you could use, akin to FEC. Haven't looked at your site yet, will be interested to see what you've built :)

Edit: I checked it out, nice, I like the lower res stenography approach, can work very nicely with good upscaling filters - gave it a star :)

>Let's crop it anyway

That is not cropping.

https://en.wikipedia.org/wiki/Cropping_(image)

>Cropping is the removal of unwanted _outer_ areas from a photographic or illustrated image.