[eru]

If you can get all the pixels back exactly, getting the original jpeg back would only require a very small amount of extra data.

But it might be more hassle than it's worth it to create the code and algorithms to do so.

[janwas]

Hi, we indeed support byte for byte reconstruction of the original JPEG codestream.

[eru]

Interesting!

Btw, if memory serves right, Google Photos deliberately gives you back the same pixels but not the same JPEG codestream bits under some circumstances. That's too make it harder to exploit vulnerabilities with carefully crafted files.