Guetzli is a lossy image compression tool and perceptual JPEG encoder. It converts PNG or JPEG inputs into high-density JPEG files, reducing file size by removing data that the human eye cannot easily detect.
The tool utilizes human vision models to optimize the balance between file size and visual fidelity. It employs perceptual quality metrics and psychovisual similarity estimation to maintain high visual quality while maximizing compression density.
The project includes a visual difference analyzer capable of generating spatial difference heatmaps and calculating scalar similarity scores. These utilities allow for the comparison of compressed images against original reference sources to identify and quantify visual artifacts.