發表於 2017-3-20 23:02:37
Full story: http://www.pcmag.com/news/352439 ... sizes-by-35-percent|
The new open source algorithm is called Guetzli, which is Swiss German for "cookie." Guetzli manages to significantly reduce file size without breaking compatibility with the JPEG standard, web browsers, and image processing applications. That's important, as it means the algorithm can be used everywhere without anything else having to change.
The three images below attempt to demonstrate how well Guetzli works. The uncompressed image is on the left, the libjpeg version is in the middle, and the Guetzli version is on the right. If you can't tell the difference, Guetzli has done its job.
The encoding process for a JPEG can be broken down into six distinct parts: color space transformation, downsampling, block splitting, discrete cosine transform, quantization, and entropy coding. Each can be optimized, and Guetzli focuses specifically on the quantization stage as this is typically where visual quality is lost.
Guetzli is good news for everyone. Smaller file sizes means less data is being transferred around the Internet and websites will load faster. Another upside is that the transition to using Guetzli will happen quietly in the background without any disruption to that next image search you perform looking for cute cats.