LOW-BIT-RATE CODING OF UNDERWATER VIDEO USING WAVELET-BASED COMPRESSION ALGORITHMS

Recent advances in autonomous underwater vehicle (AUV) and underwater communication technology have promoted a surge of research activity wi thin the area of signal and information processing. A new application is proposed herein for capturing and processing underwater video onboa rd an untethered AW, then transmitting it to a remote platform using a coustic telemetry. Since video communication requires a considerably l arger bandwidth than that provided by an underwater acoustic channel, the data must be massively compressed prior to transmission from the A UV. Past research has shown that the low contrast and low-detailed nat ure of underwater imagery allows for low-bit-rate coding of the data b y wavelet-based image-coding algorithms. In this work, these findings have been extended to the design of a wavelet-based hybrid video encod er which employs entropy-constrained vector quantization (ECVQ) with o verlapped block-based motion compensation. The ECVQ codebooks were des igned from a statistical source model which describes the distribution of high subband wavelet coefficients in both intraframe and predictio n error images. Results indicate that good visual quality can be achie ved for very low bit-rate coding of underwater video with our algorith m.