Stimulated by the increasing availability of digital transmission and the evolution from application specific network to integrated service networks, cost effective transmission for sophisticated video service will become more economic and widespread in the near future. Videocoding technology has been evolving over the past 20 years beginning with DPCM, entropy coding and run-length coding, followed by motion detection/compensated coding and subband coding research. Psychovisual coding and knowledge-based image coding are now the major focuses in this field and, recently, only a few groups have been publishing their work in this area. The common research interests in this field is to investigate a new ways of improving picture quality significantly at adequately low bit rates. Because of dynamic bandwidth allocation of transmission and resource sharing, video transmission is no longer limited to a particular transmission rate ih the coming generation of packet-switched networks. The development of variable-bit-rate compression techniques that can guarantee constant image quality at the destination in packet-switched network applications will be a research thrust now for integrated service networks. In this paper, the up-to-date research efforts in the areas of psychovisual coding, knowledge-based image coding and variable-bit-rate compression will be discussed. The effectiveness and the simulations results of our variable-bit-rate compression and a psychovisual coding techniques will be presented. In addition, several open research topics will be briefly pointed out in each subject.