A new image format for the Web developed by Google

WebP logo

WebP is a new image format that provides lossless and lossy compression for images on the web. WebP lossless images are 26% smaller in size compared to PNGs. WebP lossy images are 25-34%
smaller in size compared to JPEG images at equivalent SSIM index. WebP
supports lossless transparency (also known as alpha channel) with just 22% additional
bytes. Transparency is also supported with lossy compression and
typically provides 3x smaller file sizes compared to PNG when lossy
compression is acceptable for the red/green/blue color channels.

Webmasters and web developers can use the WebP image format to
create smaller and richer images that can help make the web faster.

How WebP works

Lossy WebP compression 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.

Lossless WebP compression uses already seen image fragments
in order to exactly reconstruct new pixels. It can also use a local
palette if no interesting match is found. This palette is continuously
updated to re-use recent colors. This compression mode is named “VP8L”
and shares some common features with the so-called LZ77 compression algorithm.

A WebP file consists of VP8 or VP8L image data, and a container based on RIFF. The standalone libwebp library serves as a reference implementation for the WebP specification and is available at this git repository and as a tarball.

WebP support

WebP is supported by a variety of tools. In addition, it is now natively supported in Google Chrome, the Google Chrome Frame plug-in for Internet Explorer, Opera 11.10 and Android Ice Cream Sandwich.

Developers have also added support to a variety of image
editing tools. This release also provides a lightweight encoding and
decoding library, libwebpand command line tools cwebp and dwebp for converting images to and from the WebP format. The full source code is available on the download page.

Convert your favorite collection from PNG and JPEG to WebP by downloading the precompiled cwebp conversion tool for Linux, Windows or Mac OS X.