Subband image coding using a fixed-rate lattice vector quantizer

Abstract

We present a fixed-rate lattice VQ (FRLVQ) for subband image coding. The fixed-rate lattice VQ is an extension of the entropy-coded lattice vector quantizer (ECLVQ) [Mohdyusof and Fischer, 1994]. For an error-free channel, image coding using ECLVQ provides competitive performance with other methods. ECLVQ is a variable length coder, hence a single bit error in the encoded bit stream could lead to error propagation resulting in severe degradation in image quality. A fixed-rate lattice VQ is constructed from the ECLVQ by grouping together several vectors as a The macroblock is encoded at a fixed rate, while allowing a variety of encoding rates for each vector in the macroblock. In the event of a transmission error, error propagation is confined to that particular macroblock. In this work we assume the encoded bit stream is transmitted over a binary symmetric channel. The simulation results show that the FRLVQ subband image coding provides competitive performance with other fixed-rate image coding systems. The simulation results also indicate FRLVQ performance degrades gracefully in the presence of channel noise.