In the latest versions of Safari desktop/iOS, there is no specificity in image request headers that indicates the browser supports jpeg 2000. Ideally, we would have something like "image/jp2" and/or "image/jpeg2000" in the accepts header, analogous to Google's Chrome which adds the "image/webp" entry in the accepts header. This would be extremely helpful so that server side image processing tools (like Thumbor) can "automagically" return images with the best possible encoding/compression.
Please add this header.
Jason Ormand @ Vox Media
This would be really useful for us as well. Globo.com is a large portal in south america (+1B page views/mo).
We have a big focus on speed. That's why we added Automatic WebP support for thumbor. It would be awesome to have the same level of support for Safari (Mac OS, but even more pressing iOS).
This would allow us to detect if a request can receive JPEG 2000 and if so vary our cache by the Accept header.
Hope this gets implemented.