Adaptive postfilter for low bitrate video telephony

摘要

An adaptive postfiltering arrangement for decoding video images is disclosed wherein the postfilter parameters used to control the strength of the postfilter (235) are computed by the encoder (211) at the time the video images (220) are encoded and are transmitted (on 212, 214) to the postfilter as side information contained in the video image bitstream (on 213). The postfilter removes distortions from decoded video images, derived as a result of DCT coefficient quantization errors produced when the image is compressed for transmission to a decoder, and is based on computation (on 212) of signal-to-noise ratios (SNRs), of one or more components of encoded video images. Other information about image content, such as face location information (on 214), can also be included in the side information sent to the postfilter in the video image bitstream, to modulate the postfilter strength according to the image content.