WebP

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Template: Infobox file format / Maintenance / MagischeZahlHex missing WebP

WebP ( " weppy " ) is a data format for lossy or lossless compressed static or animated images. It is a further derivative of the 2010 shared video codec VP8, a sister project of the video format WebM.

Features

It provides (only) 4:2:0 color sub-sampling. It supports images with side lengths of up to 16,383 (14 bits: 214-1 ) pixels.

WebP achieved at very high compression more image quality per amount of data than JPEG, but is subject tends to be at medium to high quality settings. It is particularly effective in compressing of low detail, uniform image parts.

On 3 October 2011, support for animation, ICC profile, XMP metadata and tiling for WebP (large, composite images from max. 16384 × 16384 parts ) were introduced. 18 November 2011 experimentally lossless compression and support for transparency (alpha channel) were both introduced in lossy as well as lossless mode. The support has been enabled by default with the introduction libwebp 0.2.0 (16 August 2012).

The software for processing and display of WebP is released under the BSD license.

Technology

The format is developed by Google based on the intra-frame coding of the video codec VP8 and the RIFF container format and is compatible with VP8 bitstream. As such, it is a block-based (4 × 4 pixel block size) transformation method with eight -bit color depth and a brightness-color - color model with color subsampling in the ratio 1:2 (YCbCr 4:2:0 ). It uses a relatively advanced entropy - a kind of binary arithmetic coding ( CABAC similar ). The obligatory RIFF container leads without further content to an overhead of only 20 bytes and can serve the additional inclusion of metadata.

The free reference implementation consists of a picture conversion software in the form of a command line program for Linux ( webpconv ) and a program library for decoding ( the same as for WebM ).

Use

The format is intended to serve as a new open standard for lossy compressed true-color graphics on the Web and is placed as a direct competitor to the older JPEG, against which it is to allow much smaller files at comparable quality.

Supported Web Browsers

As the first Web browser Google's own web browser Chrome the format since version 9.0.568.0 dated 29 October 2010; Opera since version 10.11.2042 of 15 March 2011. For Firefox since early October 2010, a patch is available, however, for the WebP support in current form was rejected in Mozilla products for the time being because the format still no clear advantage over JPEG offers. Moreover, the developers have already submitted a patch for the rendering engine WebKit, the support in the whole series brings WebKit - based browser.

In April 2013 Mozilla announced after the request of several unnamed major website operators to examine the need for WebP again. Google WebP was added at this time to many of the previously missing from Mozilla functions. A decision on the admission is still pending.

Use Opera since version 11:10 on 12 April 2011, the default format for images to be compressed transmitted via Opera's proxy server for the " Opera Turbo ".

Konqueror, the KDE web browser, the WebP support from the KDE Version 4.11. Since the image formats are implemented in KDE as reusable components, thus, any graphics program to use under KDE WebP (eg KolourPaint, Gwenview, Krita, Calligra, ...)

An implemented in the programming language Java VP8 decoder is available as free software. This WebP can also be used in Java - enabled browsers that do not support the format itself.

Criticism

The first publication presented in format and its (reference) implementation are considered still remarkably useless. Jason Garrett -Glaser, a developer of x264 encoder, expressed several criticisms about WebP. WebP support only the color sub-sampling 4:2:0. Supported by the JPEG format 4:2:2 and 4:4:4 were missing. The quality of images in comparison WebP format is apparently in spite of the superior format at the same file size poor and blurred than those in JPEG format, since the encoder may establish no perceptual psychology optimizations. Since then, Pascal Massimino, the developer of cwebp encoder, improves this and eliminated most of the annotated error, whereby the above-mentioned points are mostly obsolete. Jason Garrett -Glaser correctly points out that the H.264 intra -frame algorithm provides better results than VP8, but contrary to VP8 encumbered by patents.

Mozilla refused WebP support for its products until March of 2013, because the format still no clear advantage over JPEG offering: comparative tests tend to show at medium to high quality settings in superior compression results and difficulties with attention to detail images.