A new algorithm with conditional pictureelement replenishment is proposed in this paper

which is called CRCC/CDC. The cluster coding and combination difference coding are effectively used to reduce the number of bits to be transmitted

and the new coding mode and parameter control methods have been devised to prevent buffer memory from overflow. It has been determined by computer simulated experiment that the encoded picture Quality is good and the signal to weighted Quantizing noise ratio is 45 dB at 0.2 bit/pel

which is similar to the videoconferencing signal at a bandwidth of 4 MHz to be transmitted at bit rate of 2 Mb/s. The （?）ffect due to the transmission error with this algorithm is also discussed.