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: 0) by Anonymous Coward on Monday March 20 2017, @01:51PM
If I stream a HD video, it is my decision, and I'll do that decision based on the current connection. If I decide that at my current available bandwidth/data I cannot afford streaming HD I won't do it (indeed, likely I won't stream video at all). When I'm using my fat DSL at home, I don't mind HD streams, nor big images. However I have little control over the bandwidth used by the images embedded into a web page.
That's what ad blockers and related technologies are for (or rather, against).
A professional photographer will use a camera that stores raw images. Note that PNGs aren't raw images either, as even the step going from sensor data to a viewable image consists of considerable processing (for example note that unless you've got a really expensive camera, on your camera there's only one physical colour channel for each pixel, while all the other channels are interpolated from the surrounding pixels; cameras which have full colour on all pixels are expensive because of the additional optics and extra CCDs required).