[jws]

As you get to small image sizes, the relative size of the quantization table and the Huffman encoding table becomes significant. You can easily just pick a standard version of these, leave them out of the image (which is no longer a valid JPEG), and then put them in at the destination to make a valid JPEG again.

I'm not finding a source, but I think I remember the tables being in the 1-2kB range.

Cheap MJPEG USB cameras do this. Their streaming data is like JPEG but without the tables since it would take up too much bandwidth.

[canucker2016]

Mentioned the FB blog post in my comment to this post. I didn't see any mention of the size of the fixed tables.

see https://news.ycombinator.com/item?id=35268708

[georges_gomes]

This technic is very interesting. I imagine quite effective and very small JavaScript decoded.