Stephen Shankland/CNET

Firefox has joined Google's WebP party, another endorsement for the internet giant's effort to speed up the web with a better image format.

Google revealed WebP eight years ago and since then has built it into its Chrome web browser, Android phone software and many of its online properties in an effort to put websites on a diet and cut network data usage. But Google had trouble encouraging rival browser makers to embrace it.

Mozilla initially rejected WebP as not offering enough of an improvement over more widely used image formats, JPEG and PNG. It seriously evaluated WebP but chose to try to squeeze more out of JPEG. But now Mozilla -- like Microsoft with its Edge browser earlier this week -- has had a change of heart.

"Mozilla is moving forward with implementing support for WebP," the nonprofit organization said. WebP will work in versions of Firefox based on its Gecko browser engine, Firefox for personal computers and Android but not for iOS. Mozilla plans to add support in the first half of 2019.

Committing to a new image format on the web is a big deal. In addition to technical challenges and new security risks, embracing a new image format means embracing it for years and years, because removing support at some point in the future will break websites that rely on it.

It's one of the central conundrums of the web. Browser makers and website developers want to advance the technology, but they can't remove older aspects of the foundation as readily as Google can with Android or Apple with its rival iOS software. Websites have a long shelf life.

There are exceptions. Browser makers remove some undesirable interfaces, usually after careful measurement of usage and careful assessment. But it's harder for widely used technology like Adobe Systems' Flash Player. We're several years into a very slow burial of that software foundation. Browser makers and eventually Adobe, too, concluded Flash's security and stability problems deemed it no longer were worthwhile. Ditching it was made possible by years of work building Flash's abilities into the web itself.

Why the change of heart?

"We are seeing a number of developments coming together that might lead to an accelerated adoption of WebP," including Edge support, Mozilla said.

Mozilla is a major backer of another image format under development, AVIF. Where WebP is based on Google's VP8 video compression technology, AVIF is based on a newer video format called AV1 from a much broader group, the Alliance for Open Media. That alliance includes a lot of heavy hitters, including Google, Apple, Microsoft, Cisco, Amazon, Netflix and Facebook, but most of its work is focused on the AV1 video format.

"We also look forward to AVIF being ready, and we will continue to invest in it," Mozilla said.

Apple briefly dabbled with WebP support in test versions of its Safari browser but removed that support, an inconvenience for any developers who want to use the format but also have to ensure their websites work on iPhones and iPads. Apple declined to comment.

First published October 5, 10:02 a.m. PT.

Update, 2:43 p.m. PT: Adds further comment from Mozilla.

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