WebP, a new image format for the Web (The Chromium Blog)

Or how it compared simply more advanced JPEG encoders— none of the widely used jpeg encoders use things like RDO optimization or activity masking, techniques which are used to great effect in the better video encoders.

Additionally, if the internet is to deploy something new (not the stuff that I just named) why should it be something technologically contemporary to about 2003/2004? There has been a lot of exciting image coding research and results since then, e.g. http://www.ponomarenko.info/adct.htm and https://sites.google.com/site/dlimagecomp/Home (plus a lot of other things which only exist as academic papers right now). VP8 even lacks some of the things that contemporary video codecs have which would be useful like adaptive quantization.

And one without an efficiently coded alpha channel and scalability to lossless? I find it really hard to believe that something will be widely adopted unless it satisfies a broad set of needs— otherwise we're left with JPEG being "good enough and widely compatible"

With only 4:2:0 colorspace it means that if size is no object plain JPEG will still deliver better quality on many images.

It's also disappointing that the performance numbers are fairly vague— "without perceptibly compromising visual quality" isn't defined. I could take a regular JPEG encoder and re-compress a great many files "without perceptibly compromising visual quality" and get some savings. Whats the additional improvement beyond that? How does JPEG+Arith, JP2K, and JPEG XR compare? ... They don't even get mentioned, for some reason. Much less the state of the art research codecs.

I'd be surprised if the improvement weren't _less_ from uncompressed originals— the jpeg compressed files already have JPEG like nose, if your codec is reasonably good at recompressing block-DCT like noise then you'll do fairly well on already compressed inputs. Though we don't even know what the improvement really is because they didn't give numbers for the same recompression trick with plan jpeg.

It's interesting for sure— and the web could certainly use a better format for continuous tone images. But it could also use lossless support, alpha channels, and there are already several more mature contenders that offer these things. As of right now it sounds to me like a somewhat myopic improvement which may only be attractive someone who already has a VP8 decoder, needs to squeeze down their bandwidth bills, doesn't care about all the other features lacking in JPEG, and controls both the server and the client.

Oh well— at least it has metadata, unlike webm. ;)