Hundreds of steganography tools already exist for making images which can be shared on any medium where recompression is not an issue (http://www.jjtc.com/Steganography/tools.html). In this case I wanted to provide a simple user experience and also handle Facebook's recompression specifically.

In the future this tool could be extended to other sites which recompress images when they're uploaded although it would certainly be a more confusing user experience.