Fuzzy-Controlled Perceptual Coding of Videophone Sequences

This paper describes a fuzzy quality-controller for video coding systems based on the H.261 recommendation. The picture quality is tuned by a classification of the blocks of each frame of the sequence based on a simplified model of the human visual system. The quantization parameter is evaluated according to this classification making more relevant parts be coded with finer details at the expense of less significant regions. The system is based on a restricted number of fuzzy rules and can be easily reconfigured if a different classification criterion must be adopted. The subjective quality of coded sequences is better than the one obtained by the reference model at the cost of higher computational tasks.