Google has announced that it has developed a new open source encoder called "Guetzli" for compression of JPEG files. The algorithm used by the company allows it to compress JPEGs by up to 35% more than currently available methods. This will enable webmasters to develop webpages that can load faster while using comparatively less data.
Google has stated that "Guetzli" - which means "cookie" in Swiss German - targets the quantization stage of a JPEG image which is partly responsible for visual quality. The company went on to say that:
Guetzli strikes a balance between minimal loss and file size by employing a search algorithm that tries to overcome the difference between the psychovisual modeling of JPEG's format, and Guetzli’s psychovisual model, which approximates color perception and visual masking in a more thorough and detailed way than what is achievable by simpler color transforms and the discrete cosine transform.
Google has cautioned that while its algorithm manages to significantly compress JPEG files with minimal loss in visual quality, the drawback is that the compression process requires considerably more time than current methods.
That said, it did point out that when humans were shown images compressed by Guetzli and libjpeg, they consistently preferred the quality of the former - even when the size of the libjpeg images was slightly larger. According to Google, this makes the slower compression a "worthy tradeoff".
Google hopes that the algorithm used in its Guetzli encoder will enhance the performance of webpages, allowing for less bandwidth usage and faster loading times. It also aims to enhance usability for graphic designer, in addition to aiding future research on video and image compression techniques. You can view Guetzli's repository on GitHub here.