A memory-efficient fast encoding method for vector quantization using 2-pixel-merging sum pyramid

Zhibin Pan, Koji Kotani, Tadahiro Ohmi

Research output: Contribution to journalConference articlepeer-review

3 Citations (Scopus)


Vector quantization (VQ) is a famous signal compression method. In. a framework of VQ encoding, the fast search method for finding the best-matched codeword (winner) is a key issue because it is the time bottleneck for practical applications. To speed up VQ encoding process, some fast search methods that are based on the concept of multi-resolutions by introducing a pyramid data structure have already been proposed in previous works. However, there still exist two serious problems in them. First, they need a lot of extra memories for storing all purposely-constructed intermediate levels in a pyramid, which becomes an overhead of memory. Second, they completely discard the obtained Euclidean distance that has already been computed at an intermediate level whenever a rejection test fails at this level during a search process, which becomes an overhead of computation. In order to solve the overhead problems of both memory and computation as described above, this paper proposes a memory-efficient storing way for a vector and a recursive computation way for Euclidean distance level by level based on a 2-pixel-merging (2-PM) sum pyramid, which can thoroughly reuse the obtained value of Euclidean distance at any level to compute the next rejection test condition at a successive level. Mathematically, this method does not need any extra memories at all and can reduce the original computational burden that is needed in a conventional non-recursive computation way to about half at each level. Experimental results confirmed that the proposed method outperforms the previous works obviously.

Original languageEnglish
Pages (from-to)III669-III672
JournalICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings
Publication statusPublished - 2004
EventProceedings - IEEE International Conference on Acoustics, Speech, and Signal Processing - Montreal, Que, Canada
Duration: 2004 May 172004 May 21

ASJC Scopus subject areas

  • Software
  • Signal Processing
  • Electrical and Electronic Engineering


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