On the Limits of Perceptually Optimized JPEG

The study presented in this paper aims at quantifying the empirical limits of JPEG optimization, when the compressed stream is standard compliant and only the quantization tables are optimized. Image-dependent quantization tables, which minimize the bitrate of the compressed image while maintaining transparent visual quality, are identified by means of a psychovisual experiment. The results demonstrate that significant room for improving JPEG compression efficiency is available.