Apparently, Google isn’t done trying to take over the Internet. After announcing the WebM video format earlier this year, the company has now revealed another, similar project: WebP, which is meant to replace JPEG as the standard for lossy image compression on the web. No kidding. Google has written about the endavor on its Chromium Blog, and it’s even released some tools so developers can get their hands dirty with the format already.
These two paragraphs from the blog post sum up the endeavor pretty well. In a nutshell, Google says 65% of the data transferred over the web today are images, and it wants to introduce a more efficient format to speed things up.
To improve on the compression that JPEG provides, we used an image compressor based on the VP8 codec that Google open-sourced in May 2010. We applied the techniques from VP8 video intra frame coding to push the envelope in still image coding. We also adapted a very lightweight container based on RIFF. While this container format contributes a minimal overhead of only 20 bytes per image, it is extensible to allow authors to save meta-data they would like to store.
While the benefits of a VP8 based image format were clear in theory, we needed to test them in the real world. In order to gauge the effectiveness of our efforts, we randomly picked about 1,000,000 images from the web (mostly JPEGs and some PNGs and GIFs) and re-encoded them to WebP without perceptibly compromising visual quality. This resulted in an average 39% reduction in file size. We expect that developers will achieve in practice even better file size reduction with WebP when starting from an uncompressed image.
A gallery with some WebP image samples is up, as well. I’ve gotta say, the WebP shots look pretty darned good considering their purportedly smaller file sizes. The JPEGs seem to look a tad sharper, but it’s hard to tell the difference without looking really closely.