This looks nice, bookmarked!
Maybe expose some simple quality setting to the user?
As far as I can tell after glancing at the code, the only optimization that's done is re-encoding the image with quality set to 75, so a quality slider would be nice imho.
My initial plan was to replicate the functionality of tools like tinyjpg, thus just offering users a simple interface with good defaults. But I already had in mind the lossy/lossless re-encoding functionality, as well as the quality slider, which I plan to add sometimes in the future
