WebP : Java Glossary



WebP, pronounced weppy, is a new web format from Google that supports both lossless and lossy compression. Like PNG (Portable Network Graphics) it supports variable transparency — an alpha channel, even in lossy mode. WebP lossless images are 28% smaller in size compared to PNGs (Portable Network Graphics). WebP lossy images are 25-34% smaller in size compared to JPEG (Joint Photographic Experts Group) images. The extension is *.webp and the mime type is image/webp for both lossy and lossless formats.

File Formats

There is an ASCII (American Standard Code for Information Interchange) signature RIFF (Resource Interchange File Format) at offset 0x0000 and another WEBP at offset 0x0008. You can extract the width and height at offset 0x001a. At that offset are a pair of little endian 16-bit vales for width × height.


Paint Shop Pro can read and write old-style webp images with the 16-bit lengths, but not the new ones with the 24-bit lengths. IconLover does not handle them.

You can test whether it works on your browser.

Support for Webp Images
Internet Explorer

IE can support webp if you install the chrome plugin. If work in the browser, they also work in CSS (Cascading Style Sheets) style sheets. If so much as one of the major browser vendors continues to snub the format, it cannot replace png, jpg and gif. When Firefox relents, I will convert my website to webp. Facebook used it for a while to reduce the volume of traffic, but users complained because of lack of browser support.

Webp Browser Test

How it Should Look How WebP Renders
lossy lossy jpg lossy webp
lossless lossless png lossless webp

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