Very low bit rate video compression for acoustic transmission of subsea images of hydrothermal vents

A special purpose very low bit rate video compression technique is presented. This will integrate an underwater acoustic data communications system installed in an autonomous underwater vehicle. The envisaged mission includes the detection and the transmission and/or recording of images of shallow water hydrothermal vents to be remotely analyzed by marine scientists, such as biologists and geologists. Due to the high constraints imposed by the limited channel bandwidth provided by the underwater acoustic channel, only moderate transmission data rates are allowed, massive data compression being required for near real time video transmission. The authors present the results achieved with their technique using video sequences acquired at the Azores sea. Those results show that their technique can cope with the transmission rate constraints imposed by the underwater acoustic channel, and provides a very good quality of the reconstructed video sequences