Exploitation of image coherency and topology preservation to accelerate the pixel mapping stage of SOM-based image quantisation

Abstract

SOM-based image quantisation requires a considerable amount of processing time even during the pixel mapping stage. Basically, a full search algorithm is employed to find a codeword, within a codebook, whose distance to the queried pixel is minimum. In this paper, we present a novel approach to accelerate the pixel mapping stage by utilisation of the spatial redundancy of pixels in the image and the inherent topological preservation nature of the resulting codebook. The experimental results confirm that the proposed approach outperforms ordinary solutions and is comparable to state-of-the-art solutions in terms of execution time. In addition, as the proposed approach does not require codebook sorting and a complex data structure with variable sizes, this simplifies its implementation and makes it feasible for hardware realisation.

Keywords:

• coherency
• SOM quantiser
• pixel mapping
• topology preservation

This work was supported by the Thailand Toray Science Foundation and Thailand’s National Electronics and Computer Technology Center (NECTEC) under the project: a study of fall-risk affecting motion/movement parameters and development of a neuron network-based adaptive fall-risk analyser. This paper was proof-read by Professor Alan E. Middleditch and Associate Professor Dr David J. Harding. The author would like to thank all anonymous reviewers for their comments in the previous versions of this paper.