Mountain View, California — Internet search engine giant Google in its relentless efforts to make the Web faster, the company over the weekend announced that it is trimming down the size of image files, which make up about 65% of the bytes on the Web, and released a developer preview of a new open-source image format dubbed as WebP that reduces image file sizes by an average of a third more than what JPEG compression can accomplish.
Speed for Google is very essential in making Web applications and mobile applications competitive with desktop applications and to a positive user experience in general. Thus, an alternative to the JPEG format, which is typically used today for Web pictures and ima ges, WebP should “significantly” reduce the byte size of images, Google promises.
According to Google, photos and other images are the single largest factor in Web page latency, representing 65% of the bytes transmitted when a Web page request is made. While those same files re-encoded with WebP will produce files that are, on average, 39% smaller than other formats, reducing the load on servers, ISPs including mobile carriers, and the Web browser clients themselves.
So engineers at Silicon Valley search engine giant have tried to make images smaller by improving lossy image compression techniques, which tend to produce smaller image files than lossless image compression schemes. And that reduction is likely to enable Web sites to load a whole lot faster. “Images and photos… can significantly slow down a user’s Web experience, especially on bandwidth- constrained networks such as a mobile network,” Richard Rabbat, a Google product manager, wrote in a blog post.
“In order to evaluate the effectiveness of our efforts, we randomly picked about 1,000,000 images from the Web (mostly JPEGs and some PNGs and GIFs) and re-encoded them to WebP without perceptibly compromising visual quality. This resulted in an average 39% reduction in file size,” he wrote. “We expect that developers will achieve in practice even better file size reduction with WebP when starting from an uncompressed image.”
The JPEG format is the dominant lossy image file type on the Web. A standard that was originally announced in 1992. Other file formats, such as .PNG, use lossless compression, which maintains the original image data. Besides, WebP, developed using compression technology from the VP8 video codec that Google acquired from On2 and open-sourced in May, compresses image files 39% smaller on average than JPEG, based on a random sample of one million images selected from the Web.
“To improve on the compression that JPEG provides, we adopted an image compressor based on the VP8 codec that Google open-sourced in May 2010,” Rabbat, wrote in a blog post. “We applied the techniques from VP8 video intra frame coding to push the envelope in still image coding. We also adapted a very lightweight container based on RIFF.”
As a developer release, Google has unfolded a lightweight decoder for WebP files (libvpx) and a command line tool (webpconv) for converting images to the WebP format and back. Consumers would not really be able to view WebP images until Google’s engineers finish implementing WebP in the company’s Chrome Web browser.
But the company has formulated a preview gallery for those who wish to do a side-by side comparison. Because WebP is not yet supported in any browser, Google has wrapped the WebP images in a PNG frame so they can be displayed. Google said it plans to add support for WebP in Webkit, as well as Chrome, together with support for alpha-layer transparencies.
Dan Olds, an analyst with The Gabriel Consulting Group, stated that this level of file size shrink could greatly speed up transferring of images. The issue will be making WebP a standard in a JPEG world.
“If it were to be standardized, it could encourage performance gains on a wide range of applications, not just Interenet content. However, this is not anywhere close to a slam dunk,” Olds said. “First, the new format would have to be able to offer the same range of quality as JPEGs. And the JPEG standard is universal, and it is going to take a huge effort to replace it with another format no matter how much better it might be.”
Google has also provided a statistical evaluation of the new format here, where the company correlates WebP to JEPG2000 and JPEG, finding it especially useful on small image sizes. According to one commenter on Google’s blog post, Google has limited the WebP maximum file size to 16383 x 16383.
Now those curious about SEO will probably find the rank of the format worth paying attention to, as Google recently announced that it now counts page speed as a ranking factor. Just remember, page speed is only one of about 200 ranking factors Google takes into consideration.