Guetzli is a JPEG encoder that aims for excellent compression density at high visual quality. Guetzli-generated images are typically 20-30% smaller than images of equivalent quality generated by libjpeg. Guetzli generates only sequential (nonprogressive) JPEGs due to faster decompression speeds they offer. Get a copy of the source code, either by cloning this repository, or by downloading an archive and unpacking it. Install libpng. If using your operating system package manager, install development versions of the packages if the distinction exists. Run make and expect the binary to be created in bin/Release/guetzli. Note that Guetzli is designed to work on high quality images. You should always prefer providing uncompressed input images (e.g. that haven't been already compressed with any JPEG encoders, including Guetzli). While it will work on other images too, results will be poorer. You can try compressing an enclosed sample high quality image.