Fast codebook search algorithms for VQ of wavelet images

Two fast codebook search algorithms are proposed for vector quantization (VQ) encoding in wavelet/VQ coding schemes. These algorithms complement the partial distance elimination (PDE) algorithm by satisfying the premature exit condition in an early stage. The algorithms are especially appropriate for high vector dimension. Furthermore, any triangular inequality elimination (TIE) methods which reduce the search space can be integrated with our methods to further save the encoding time. The computational complexity is reduced by exploiting the property of the wavelet domain in which large coefficients rarely exist. Experimental results confirm the effectiveness of the proposed algorithms.