Beyond their awesome work on Zopfli and Brotli, Google has brought their expertise in compression to bear on video and image formats. One of the most interesting of these efforts is WebP, an image format designed to replace the aging JPEG (lossy) and PNG (lossless) image formats.
WebP offers more efficient compression mechanisms than both PNG and JPEG, as you can see in this comparison of a few PNG files on Google’s top sites vs. WebP-Lossless versions that are pixel-for-pixel identical:
You can see these savings everywhere, from Google’s homepage logo, which is 3918 bytes (29%) smaller, to Google applications’ image sprites (59% smaller!) to advertisements served by Google’s ad network (18% smaller). These compression savings are much greater than those provided by Zopfli, which is constrained by compatibility with the legacy PNG format.
As an additional benefit, WebP files don’t contain the sort of metadata bloat found in PNG, JPEG, and GIF.
So, the bandwidth and cache-size savings are obvious.
While the format is currently only supported in Chrome and Opera, web servers can easily serve WebP to only clients that request it via the Accept header:
This approach to WebP adoption is in use today by major sites like the Washington Post.
Google invented the format, so it’s not a case of “not-invented-here.”
The non-adoption of their own format leads to a troubling question—is there something about WebP that Google isn’t telling us? Surely there must be a good reason that Google’s own properties aren’t reaping the benefits of the format they’ve invented?
Update: Alex Russell retorts “uh, we use webp in TONS of places.”