Face-based visually-optimized image sequence coding

We have developed a coding technique which exploits characteristics of the human visual system to allocate more bits to the region in which a viewer is most likely, and assumed, to be looking. We focus on applications, such as video phone and video teleconferencing, in which the regions of interest are those containing human faces. Our approach encodes the video frames more efficiently than uniform quantization and can be used to significantly reduce the encoding bit rate or to improve the perceived image quality for a given bit budget. The method consists of the following: face detection and tracking, local visual-sensitivity determination, and quantizer control.