Google has developed and open-sourced a new JPEG algorithm that reduces file size by about 35 percent—or alternatively, image quality can be significantly improved while keeping file size constant. Importantly, and unlike some of its other efforts in image compression (WebP, WebM), Google's new JPEGs are completely compatible with existing browsers, devices, photo editing apps, and the JPEG standard.
The new JPEG encoder is called Guetzli, which is Swiss German for cookie (the project was led by Google Research's Zurich office). Don't pay too much attention to the name: after extensive analysis, I can't find anything in the Github repository related to cookies or indeed any other baked good.
There are numerous ways of tweaking JPEG image quality and file size, but Guetzli focuses on the quantization stage of compression. Put simply, quantization is a process that tries to reduce a large amount of disordered data, which is hard to compress, into ordered data, which is very easy to compress. In JPEG encoding, this process usually reduces gentle colour gradients to single blocks of colour and often obliterates small details entirely.
The difficult bit is finding a balance between removing detail, and keeping file size down. Every lossy encoder (libjpeg, x264, lame) does it differently.
(Score: 2, Interesting) by Anonymous Coward on Sunday March 19 2017, @10:55PM
Google serves up thumbnails that they have created using a JPEG encoder. These are accessed billions of times (youtube, search, google images, etc.) They are in a key position to optimize the amount of data they send. On that scale, this does matter, and it is not an arms race. Netflix, Amazon, and others can benefit from this.