A fast search algorithm for vector quantization using a directed graph

A fast search algorithm for vector quantization (VQ) is presented. This approach provides a practical solution to the implementation of a multilevel search based on a special designed directed graph (DG). An algorithm is also given of the optimal DG for any given practical source. Simulation results obtained from applying this approach to still images have shown that it can reduce the searching complexity to 3% of the exhaustive search vector quantization (ESVQ) while introducing only negligible searching errors. It has also been shown that the searching complexity is close to a linear growth with the bit rate rather than an exponential growth in ESVQ,.