Oct 2, 2010

WebP: Google's new image format

Google has released a new image format called WebP, pronounced as "WEPPY" which reduces your size, bandwidth and hosting costs for images.This new image format reduces the file size by 40% compared to JPEG without compromising the quality. Also Google has  open sourced this format.
WebP is a method of lossy compression that can be used on photographic images. The degree of compression is adjustable so a user can choose the trade-off between file size and image quality.

A WebP file consists of VP8 image data, and a container based on RIFF. Webmasters, web developers and browser developers can use the WebP format to create smaller, better looking images that can help make the web faster.
Working of WebP

WebP uses predictive coding to encode an image, the same methodology used by the VP8 video codec to compress keyframes in videos. Predictive coding uses the values in neighboring blocks of pixels to predict the values in a block, and then encodes only the difference (residual) between the actual values and the prediction. The residuals typically contain many zero values, which can be compressed much more effectively. The residuals are then transformed, quantized and entropy-coded as usual. WebP also uses variable block sizes.

for more information visit http://code.google.com/speed/webp/