Practical methods for speeding-up the pairwise nearest neighbor method

Abstract

Listen

Translate article

The pairwise nearest neighbor (PNN) method is a simple and well-known method for codebook generation in vector quantization. In its exact form, it provides a good-quality codebook but at the cost of high run time. A fast exact algorithm was recently introduced to implement the PNN an order of magnitude faster than the original O(N 3 K) time algo- rithm. The run time, however, is still lower bounded by O(N 2 K), and therefore, additional speed-ups may be required in applications where time is an important factor. We consider two practical methods to reduce the amount of work caused by the distance calculations. Through experi- ments, we show that the run time can be reduced to 10 to 15% that of the original method for data sets in color quantization and in spatial vector quantization. © 2001 Society of Photo-Optical Instrumentation Engineers.