WebP, new graphic format from Google
The new graphic file format invented by Google wants to compete with the JPEG format with more modern technologies. It is provided under a free license.
WebP (tobe pronounced "weppy") is more efficient than JPEG and allows a faster decompression. Intended to include images in web pages, it will allow a faster loading and display and is also a part of the policy of Google for a faster Web.
The method is lossy, unlike PNG: the more your increase the compression ratio and the more the image loses accuracy.
The container file format is derived from the Resource Interchange File Format, or RIFF. It is already used by AVI and WAV sound files.
It costs 20 bytes per frame and is extensible. You can put multiple images in a file and create animations.
The compression method is based on the codec VP8 used by WebM. A predictive coding uses codes of neighboring pixels in a block to predict the values in the block, and encodes only the differences between the values found and the predicted values.
Transparency is not supported but will be in a future version. JPEG does not support it.
Comparison with JPEG
Google has provided several comparative examples.
First image in JPEG format. It is 1175642 bytes.
Then an image WebPI. It is 864134 bytes.
The images were captured and converted to PNG that is lossless.
A comparison with JPEG 2000 also shows an advantage for WebPI.
This new format is superior to JPEG and will also offer more possibilities with transparency and animation. But it will take years before it becomes a Web standard.
To address this problem, Google ask webmasters to test whether the browser supports the format, and if so, to load a WebP version of the image.
Something which is entirely possible on the pages containing picture galleries.
Also note that computers already supporting WebM support WebP too.