We propose a novel method for fast codebook searching in self-organizing map (SOM)-generated codebooks. This method performs
a non-exhaustive search of the codebook to find a good match for an input vector. While performing an exhaustive search in
a large codebook with high dimensional vectors, the encoder faces a significant computational barrier. Due to its topology
preservation property, SOM holds a good promise of being utilized for fast codebook searching. This aspect of SOM remained
largely unexploited till date. In this paper we first develop two separate strategies for fast codebook searching by exploiting
the properties of SOM and then combine these strategies to develop the proposed method for improved overall performance. Though
the method is general enough to be applied for any kind of signal domain, in the present paper we demonstrate its efficacy
with spatial vector quantization of gray-scale images.
Keywords Vector quantization - Image compression - Self-organizing map (SOM) - Topology preservation - Fast codebook search