WebP, Google's answer to JPEG, gets better quality

Google has improved the quality of WebP, an image format it promises will speed up the Web--if the company can just convince people to use it instead of JPEG.

WebP, unveiled last year, is a still-image variation of the company's open-source, royalty-free WebM video technology. Google's sales pitch: with its newer compression technology, Web pages will load faster and less network bandwidth is necessary compared to using JPEGs.

Now the company argues that it's improved quality of WebP images through more elaborate encoding software. It can, for example, concentrate its data on the complicated parts of images. And a "fancy upsampler" smooths diagonal edges that otherwise would be prone to artifacts. The improvements don't require new decoding technology, too.

"WebP's compression algorithms have been significantly improved while remaining completely compatible with the previous releases," said Google product manager Richard Rabbat and programmer Pascal Massimino in a blog post last week. Better quality compression means an image can look better at a given file size or match earlier quality without taking up as much storage space and network data.

WebP is one example of the Google obsession to rebuild the Web in faster form. Google is working on many others, ranging from reworking basic communcations protocols with SPDY and preloading some Web pages in the Chrome browser to penalizing slow Web sites in its search-ad business. Another technology, called SSL False Start, cuts the time it takes to set up a Web connection--by 30 percent, the company said at its Google I/O conference.

WebP has major challenges, though. The biggest is convincing backers of the universally supported and very well understood JPEG, but there are others, too: persuading browser makers and Web developers to use WebP, adding features to match JPEG or improve on it, and assure tech companies that they can feel confident in relying on something that's not standardized.

Major new WebP features
Standardization today probably would be premature, though: WebP is being put through the Google wringer of release early, iterate often.

"It's an image format we're looking at to grow in the future. It's still young, and we're adding some more things," Rabbat said in a Google I/O talk. Among the upcoming WebP features:

• Alpha channels for transparency--an important feature that JPEG lacks--will come to the next version of WebP. That will let designers designate areas of an image as transparent, which can be useful in contexts such as overlaying graphics on different colored backgrounds.

• Aiding the transparency technology will be a lossless compression option that can be used for when the highest image fidelity is needed. That, along with transparency, could mean Google might position WebP as an alternative to the PNG (Portable Network Graphics) standard, too.

The improved WebP encoder also handles diagonal edges better, with fewer artifacts, Google said.

(Credit: Google)

• WebP will be able to accommodate metadata, the increasingly important mechanism to embed data such as camera exposure information or photo captions within the photo file, but it won't use the EXIF technology that cameras use to record some data. Specifically, Google will use Adobe's XMP (Extensible Metadata Platform) technology.

"We want to support people's need for metadata, and we're adding XMP support," Rabbat said. "We know some people are used to EXIF, but EXIF has been painful for lots of people because there's no real standard around it. It just creates problems for the Web. Because this is a format we want to have for many years in the future, we're focusing on better, cleaner technology."

• 3D "Because we're now in a much newer world, we're adding 3D stereoscopy," Rabbat said. It'll use a multi-image technology that can package several images into one file--in this case right-eye and left-eye images. That approach will help when people want to use a single image file to reach both 2D and 3D displays, he said.

"If you look at 3D images that out there now that are in JPEG, if you display them on a 2D display, they just don't make any sense," Rabbat said. "With our ability to put multiple images in the same image file, we can call the left image vs. the right image separately."

• The multi-image technology also will help Web developers trying to use the Web pages' CSS background image technology.

"Instead of having to figure out what coordinates you're going to pick the image from, you can just refer to to the image within that multi-image format," he said; each image within the file can be referenced with a simple hashtag label. "There won't be any weird CSS to correct."