Google has been promoting the WebP still image format for some time, and lately Facebook has added its support. It’s hard to displace the well-entrenched JPEG, but it could happen. It supports both lossy and lossless compression, and Google claims it offers a significant advantage in compression over PNG and JPEG. Google says it’s free of patent restrictions; the container is the familiar RIFF. The VP8 lossy format is available as an IETF RFC; a specification for the lossless format is also available.
The container spec supports XMP and Exif metadata. Canvas width and height can be as much as 16,777,216 pixels, though their product is limited to 4,294,967,296 pixels. As far as I can tell it doesn’t support tiling, though, so partial rendering of huge images in the style of JPEG2000 may not be practical.
Chrome, Opera, and Ice Cream Sandwich offer WebP support, but not many other browsers do. Facebook’s offerings of WebP images have resulted in complaints from users whose browsers can’t read the format. The Firefox development team is starting to warm to it but hasn’t committed to anything yet. Internet Explorer hasn’t even reached that point.
It’s still early to make bets, but WebP increasingly bears watching. I’ve initiated a page for updates and errata for Files that Last with some updated information on WebP. (When I wrote the book, I couldn’t find the lossless spec.)