WebP

WebP is a lossy image format based on the image encoding used by VP8. It is presented by Google as faster alternative to JPEG.

It has been released by Google in October 2010.

WebP achieves an average 39% more compression than JPEG and JPEG 2000 while maintaining image quality. WebP is derived from WebM, Google's open-source, royalty-free technology for encoding and decoding video. The higher compression efficiency measurement came from a sample of 1 million images that Google plucked from the Web. Of them, about 90 percent were JPEG, and Google's tests showed WebP offering the same quality with 40 percent smaller file sizes. The remaining 10 percent were formats such as PNG and GIF, which are used more for illustration images such as logos rather than the photo-oriented JPEG.

Not yet in MS IE9; According to Google, the better compression rate (10-30% smaller file without loosing quality) makes difference for user experience and hosting providers (lower data volume).