WebP, a format from Google to replace JPEG
The new graphic file format invented by Google wants to compete with the JPEG with a superior format that will offer more possibilities with transparency and animation.
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.
It is provided under a free license.
Technical aspects
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.
 JPEG |
 WebP |
The images were captured and converted to PNG that is lossless and thus display all details of the image in each format.
A comparison with JPEG 2000 also shows an advantage for WebP again.
Compatibility
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.
In 2014 WebP is implemented only by Chrome and Opera, which uses the same rendering engine Blink (forked from WebKit). Facebook uses this format, but like all sites that want to do it, it installed a script to load the same image in PNG or JPEG for users of other browsers.
Also note that computers already supporting WebM support WebP too.
More information