Mozilla takes a fresh look at Google's WebP image format

Mozilla is taking a new look at the WebP image format it once rejected after some large Web sites encouraged the Firefox developer to take a fresh look and after Google released a freshly upgraded version.

WebP, which derived from the VP8 video compression technology in the WebM project Google launched three years ago, is part of the search giant's effort to speed up the Web. In WebP's case, that speedup comes through use of an image compression technology Google says produces more compact files than either JPEG or PNG.

WebP can be used where both JPEG and PNG are used today. In the former case, that's typically "lossy" compression situations, where the compression algorithm produces drastically smaller images by discarding some of the original image's information. PNG, in contrast, is often used for "lossless" compressed images such as corporate logos where the original data is intact.

WebP, though, hasn't caught on widely on the Web overall, in part because image-editing software and big-name browsers besides Google's Chrome don't support it. So the possibility of WebP support in Firefox has to be welcome news at Google.

"We decided to re-open this based on new data that shows that WebP has valid use cases and advantages," said Mozilla programmer Andreas Gal in a comment in Mozilla's bug and feature tracking system. "We will evaluate a refreshed patch and take it from there."

Google argues that WebP helped it speed page-load performance and save network bandwidth for its Google Play site, but browser makers typically are cautious about supporting new file formats on the Web. That's because support, once added, is hard to remove without breaking older Web sites that use the technology.

There's a vocal WebP advocacy community, but Mozilla is trying to keep expectations from getting out of hand.

"Just to be clear, no decision on adopting WebP has been made. The only thing that has changed is that we've just received some more interest from large non-Google Web properties which we never really had before," said Mozilla's Jeff Muizelaar in a comment on the new WebP tracking issue.

Muizelaar previously had objected to WebP because it was missing several important features. Among the missing features he pointed to:

• Support for EXIF metadata, so that information such as camera model, copyright, and exposure time can be preserved;

• Support for ICC (International Color Consortium) color profiles, for better handling of various color issues;

• Support for an alpha channel, which lets image creators designate a portion of the image as transparent.

But Google often releases technology when it's still early and raw, with the intention of improving it while it has exposure to real-world use. That's what it's been doing with WebP, adding alpha-channel support earlier.

And a week ago, Google released version 0.3.0 of the WebP library, a software utility for handling the image format. It finalized the support for ICC and EXIF metadata, too, and added support for animated WebP images, too. (Animated GIFs have become something of an art form on the Internet, breathing new life into a file format that PNG is gradually replacing.)

Google is in a powerful position to steer the Web by because millions of people use both its browser and its Web sites. That lets it bring new technology to market even without others' agreements. Although that may seem like strong-arm tactics compared to introducing new technology to standards groups, Web standards makers prefer working real-world technology than abstract ideas.

Mozilla's move, though no guarantee thus far for WebP's future, could become a major step in Google's ultimate aspiration to make WebP a Web-boosting standard. If Mozilla supports it it could persuade similar behavior among Web developers -- perhaps the same people working at the very unnamed large Web sites that nudged Mozilla to re-evaluate.