Lapped Orthogonal Vector Quantization

The block processing inherent in the use of traditional vector quantization (VQ) schemes typically gives rise to perceptually distracting blocking artifacts. We demonstrate that such artifacts can, in general, be virtually eliminated via an e cient lapped VQ strategy. With lapped VQ schemes, blocks are obtained from the source in an overlapped manner, and reconstructed via superposition of overlapped codevectors. The new scheme, which we term lapped orthogonal vector quantization (LOVQ), requires no increase in bit rate and, in contrast to other proposed approaches, no signi cant increase in computational complexity or memory requirements. Attractively, the use of LOVQ also leads to a modest increase in coding gain over traditional VQ schemes of comparable complexity. In addition to the theory, results of experiments involving speech and image sources are also presented.