Multiple description image coding using signal decomposition and reconstruction based on lapped orthogonal transforms
This paper considers the use of multiple description coding (MDC) for image transmission in communication systems where long burst errors and sometimes complete channel failures are inevitable. A general framework for MDC is proposed, which uses nonhierarchical signal decomposition at the encoder and image reconstruction at the decoder. A realization of this framework using lapped orthogonal transforms (LOTs) is developed. In the encoder, the bitstream generated by a conventional LOT-based image coder is decomposed so that each description consists of a subsampled set of the coded LOT coefficient blocks. In the decoder, instead of using the inverse LOT directly, a novel image reconstruction technique is employed, which makes use of the constraints between adjacent LOT coefficient blocks and the smoothness property of common image signals. To guarantee a satisfactory reconstruction quality, the transform should introduce a desired amount of correlation among adjacent LOT coefficient blocks. The tradeoff between coding efficiency and reconstruction quality obtainable by using different LOT bases is investigated.