Google aims to win developers over to image format WebP

February 8, 2013 by Nancy Owano report

(—In 2011, news circulated over Google's enhancements to WebP, the image format set to outdistance JPEG and, with more features in a newer version, to take on Portable Network Graphics, another graphics format. The promotional point has been that WebP can create smaller, better-looking images that can help make the web faster. Now, a Thursday posting on The Chromium Blog shows how Google is actively promoting WebP, hoping that developers and other allies will see its edge. Google announced that it started using WebP in its Chrome Web Store, with impressive results. "The Chrome Web Store uses many large promotional images and tiles on its home page, making it a very heavyweight page," wrote Stephen Konig, Product Manager, in the blog, "Using WebP to Improve Speed."

"The team was eager to find ways to improve its speed, without sacrificing the user experience or giving up image quality. WebP to the rescue!" he wrote. "By converting PNGs and JPEGs to WebP, the Chrome was able to reduce image sizes by about 30 percent on average."

's point is that the use of WebP on such a site represents important savings and valuable gains. "When you consider that over 60 percent of typical page sizes are , the benefits can be substantial. WebP translates directly into less bandwidth consumption, decreased latency, faster page loads, better battery consumption on mobile, and overall happier users," wrote Konig.

WebP is an format for Web images, based on WebM's VP8 codec. Google's reason to focus on WebP has been to reduce Web page file sizes, which in turn implies faster page-loading times, important for a Web business. "For users, the rubber meets the road when it comes to how fast the page loads though. On this score, with WebP we were able to reduce average home page load time by nearly one-third—a huge benefit for our users," said Konig.

The WebP site defines itself as a "method of lossy compression that can be used on photographic images. The degree of compression is adjustable so a user can choose the trade-off between file size and image quality. WebP typically achieves an average of 39 percent more compression than JPEG and JPEG 2000, without loss of image quality."

PNG, meanwhile, outside Google's WebP promotional quarters, is regarded as a popular image format among its fans, said to work well with line art, text, and logos. Google honed in on PNG last year in an August 2012 paper titled "Lossless and Transparency Encoding in WebP," by Jyrki Alakuijala.

The compression and decompression characteristics of WebP were compared with libpng and pngout. "We compare the resource usage of WebP encoder/decoder to that of PNG in both lossless and lossy modes. We use a corpus of 1000 randomly chosen translucent PNG images from the web, and simpler measurements to show variation in performance. We have recompressed the PNGs in our corpus to compare WebP images to size-optimized PNGs." He said the results showed that WebP was "a good replacement" for PNG for use on the regarding size and processing speed.

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1.5 / 5 (13) Feb 09, 2013
It's just another google scam to track users using images. What a low-life company. Google is trying to be one of those giant companies that dictates every aspects of our live, just like those movies, like in Lorax (off the top of my head).
4.2 / 5 (5) Feb 09, 2013
It's an open format. And the 30 percent smaller images is a valid reason for the format.
1.7 / 5 (6) Feb 09, 2013
ChangBot, your payment from M$oft an ¢rapple should be in your account and available as we type...
5 / 5 (2) Feb 09, 2013
It's just another google scam to track users using images. What a low-life company. Google is trying to be one of those giant companies that dictates every aspects of our live, just like those movies, like in Lorax (off the top of my head).

Note the irony: citing the movie instead of the book. Who's a giant company - Theodor Geisel, or Universal Pictures?
2.3 / 5 (3) Feb 09, 2013
Unfortunately it won't challenge PNG, because the people who (ab)use PNG do so because it's the default format in many software and they're lazy, or because they heard it's lossless so it must be better for everything everywhere.

Those who actually need PNG won't use WebP because they don't do the same thing. The rest will use PNG regardless because they're ignorant or stupid.
2 / 5 (4) Feb 09, 2013
Besides, they did a rather sneaky trick:

Clamp to 8 bits per component: convert input.png -depth 8 output.png

They recompressed the PNG files to assume 8 bits per component and transparency, which makes them 32 bit images, which blows up the filesize if the image in question happens to be optimized with a limited color palette.

I did a little experiment with a simple X-Y plot diagram, restricted the palette to 16 colors and saved it. Resulting file size was 17 kB. The same file upconverted to 8 bits per channel plus transparency became 37 kB.

PNG is actually not very good for full-color pictures. It's a possibility, but PNG shouldn't be used like that over the internet because it results in very large files. Any picture that requires full-color support most likely has the kind of content that is ill suited for PNG's compression algorithm.
1 / 5 (2) Feb 09, 2013
Ps. because of that, and because people misuse PNG a lot, a random selection of PNG files on the web will contain a large number of files where the content is e.g. a photograph or a screenshot of a game, which shouldn't even be done with PNG.

With that sort of material, it's easy to prove the supremacy of a format.

For example, this image should not be in PNG format: http://www.person...png8.png
1 / 5 (1) Feb 09, 2013
Eikka: Interesting. What format should your test photo be in then? Are you saying that Jpeg is superior? Is there a format that is uniformly better no matter the content (a compressed format, that is)?
1 / 5 (2) Feb 09, 2013
What format should your test photo be in then?

Quite possibly in JPEG format. If WebP is better, then that. I haven't seen the independent reviews though.

For a picture that contains few colors, which can do with a less than 256 color palette, PNG is better. For anything else, you probably shouldn't be using PNG. It was a mistake to add full-color support in PNG in the first place because it has such horrible performance (up to 5x larger files vs. JPEG at neglible difference).

5 / 5 (1) Feb 09, 2013
My understanding of PNG is that is very similar to GIF but doesn't use LZW compression since it was patented by Unisys/Compuserve.

LZW compresses repeating patterns reasonably well, so graphics containing solid colors and reduced palettes are compressed reasonably well. Photographs have less regularity and hence don't compress well with LZW or similar.
5 / 5 (1) Feb 09, 2013
It's just another google scam to track users using images. What a low-life company.

I doubt it. My wild guess is that ... Google wants more compressed images out there on the web because it directly effects it's own bandwidth and storage. Even saving a few percent would be huge, 39% is out of this world.

What I'd like is a variable quality setting in your browser so that you could speed up browsing by trading off image quality unless you specifically want to see images more clearly.
1 / 5 (2) Feb 09, 2013
My guess is that Google won't have to do much to win over web developers because, as the article states, smaller file sizes means faster page loads, and anything that can improve the performance of a developer's product is something that the developer will have no reservations about implementing.
1 / 5 (2) Feb 09, 2013
Well Google could always stuff a bit more picture-ads to a web page and retain the same loading speed. OK I know it sounds like a lame-ish reason to implement a file format.

Anyway apropos tracking looks like M$ is sponsoring a petition to stop Google to read peoples emails, at
1 / 5 (1) Feb 10, 2013
What's the technology here? Wavelets?
1 / 5 (2) Feb 10, 2013
WebP is losing more details of picture than the JPEG and it even doesn't support 4:2:2 and 4:4:4 chroma subsamplings of JPEG or alpha transparency mask of PNG. Actually it's not so difficult to achieve 40% saving of space with more aggressive compression of JPEG and you'll not recognize the difference from WebP anyway. Google should develop a good encoder first before its promotion - the opposite way will not work.
BTW Why most of comments in PO discussions are started with twaddlers, who have absolutely no idea about subject?
5 / 5 (1) Feb 10, 2013
Jpeg is superior in terms of image quality.

Is that quality needed for web page browsing?

1 / 5 (2) Feb 10, 2013
Jpeg is superior in terms of image quality. Is that quality needed for web page browsing? No.
Then you can adjust the JPEG quality during compression in such a way, you'll get picture smaller by 40% - and you're not required to implement another format. Google's problem solved.
1 / 5 (1) Feb 10, 2013
WebP is losing more details of picture than the JPEG and it even doesn't support 4:2:2 and 4:4:4 chroma subsamplings of JPEG or alpha transparency mask of PNG

Mind you, that article is three years out of date. They've added those things.

Is that quality needed for web page browsing?

Well, yes, seeing how it's supposed to be used for replacing PNG for the graphics on the facade of a website, where you'd want small files but you can't tolerate JPEG's compression artifacts.

Whenever JPEG is used for images that are downloaded a lot, the limiting factor becomes how bad you can make it look before your customers or users complain about it.

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