Enhancing selected facial features in very low bit rate video sequences

A novel approach to selectively enhance important facial features in very low bit-rate head and shoulders video sequences is described. The selected facial features (eyes, nose and mouth) are tracked from frame to frame and their positions are used to rank image blocks according to their perceptual importance. This ranked list of blocks is used to generate an independent bit stream which can be used to enhance regions of interest in the reconstructed image, depending on the available transmission bit rate. The technique is demonstrated as an add-on to an available H.263 encoder and decoder. Results are presented which show the effectiveness of the method for common image sequences.