[mwarkentin]

I believe metadata gets stripped out, which is how I get some lossless size reduction for jpgs. In my experience, this is not something that we've been interested in preserving on our images (use case - websites).

Would you be looking at using this to compress some photos for personal use, or for a photography website? What would be your use case?

[sauere]

JPGs can be optimized without losing metadata. Google "jpegtran". It does some optimizing of the data representation while staying loseless.