There are some image formats that are used for graphics online. Each of them have advantages and disadvantages and therefore requires a justification. A big advantage of JPEG files has always been the small file size – and thanks to the Google engineers you can further reduce this already small file without sacrificing quality.
Actually, you might assume that Google employees have enough to do with developing new or working on their own products. But they always look beyond the box and take care of other things that they think might be even better. So now they also created Guetzli, a JPEG encoder which can reduce the files by another 30 percent.
Google’s developers hit of course the nerve of the times, because the pagespeed is becoming more and more important for website owners and mobile loading times could benefit greatly from with Guetzli optimized JPEG’s. Of course, there are also many other encoders that can be used – with Guetzli, however, you can achieve a higher compression with better quality. Smearings only have to be made at the speed of the compression, because this requires a lot of computational effort. But this is usually done only once.