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A new image format for the Web

2016-09-01 11:30 726 查看

A new image format for the Web

目录

How WebP Works

WebP Support

WebP Converter Download

WebP is a modern image format that provides superior lossless
and lossy compression for images on the web. Using WebP, webmasters and web developers can create smaller, richer images that make the web faster.

WebP lossless images are 26% smaller in size compared to PNGs. WebP
lossy images are25-34% smaller than comparable JPEG images at equivalent SSIM quality
index.

Lossless WebP supports transparency (also known as alpha channel) at a cost of just 22%
additional bytes. For cases when lossy RGB compression is acceptable, lossy WebP also supports transparency, typically providing 3× smaller file sizes compared to PNG.

More Info
for Webmasters

How WebP Works

Lossy WebP compression uses predictive coding to encode an image, the same method 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.

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.

WebP Compression Techniques in Detail

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 from our
git repository or as a tarball.

WebP Support

WebP is natively supported in Google Chrome and the Opera browser, and by many
othertools and software libraries. Developers have also added support to a variety of image editing tools.

WebP includes the lightweight encoding and decoding library

libwebp

and
the command line tools

cwebp

and

dwebp

for
converting images to and from the WebP format, as well as tools for viewing, muxing and animating WebP images. The full source code is available on the download page.

WebP Converter Download

Convert your favorite collection from PNG and JPEG to WebP by downloading the precompiled

cwebp

conversion
tool for Linux, Windows or Mac OS X.

Tell us your experience on the project's mailing list.

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