These pictures look the same—but they're not. Because the sign on the right, hypothetically, takes up nearly 40% less space. That's the version in WebP, Google's plan to speed up the internet by slimming down its images.
What is WebP? It's a new graphics format that Google hopes will make file transfers faster than currently possible with the relatively bulky JPEG standard. WebP, like JPEG, is a method of "lossy compression," meaning that it doesn't perfectly reproduce images, but gives you a choice between file size and picture quality. THere are important differences between the two, though, according to Google:
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.
According to Google, images make up about 65% of bytes transmitted across the web today. Any way to reduce that would be hugely valuable for easing Google's tremendous network burden. That's a gigantic "would," though—JPEG is deeply entrenched on the web, and WebP files take about eight times longer to encode. There's also no browser support yet—which is why our example above is hypothetical.
Of course, native support for Chrome is all but inevitable, which means its presence on other WebKit browsers—like Safari—is equally assured. It's no easy thing, launching a new file format, but if anyone's got the scale and the determination to succeed, it's Google. [Chromium Blog, CNET]