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A Novel Encoding Scheme for Effective Biometric Discretization: Linearly Separable Subcode
Feb. 2013 (vol. 35 no. 2)
pp. 300-313
Meng-Hui Lim, Sch. of Electr. & Electron. Eng., Yonsei Univ., Seoul, South Korea
A. B. J. Teoh, Sch. of Electr. & Electron. Eng., Yonsei Univ., Seoul, South Korea
Separability in a code is crucial in guaranteeing a decent Hamming-distance separation among the codewords. In multibit biometric discretization where a code is used for quantization-intervals labeling, separability is necessary for preserving distance dissimilarity when feature components are mapped from a discrete space to a Hamming space. In this paper, we examine separability of Binary Reflected Gray Code (BRGC) encoding and reveal its inadequacy in tackling interclass variation during the discrete-to-binary mapping, leading to a tradeoff between classification performance and entropy of binary output. To overcome this drawback, we put forward two encoding schemes exhibiting full-ideal and near-ideal separability capabilities, known as Linearly Separable Subcode (LSSC) and Partially Linearly Separable Subcode (PLSSC), respectively. These encoding schemes convert the conventional entropy-performance tradeoff into an entropy-redundancy tradeoff in the increase of code length. Extensive experimental results vindicate the superiority of our schemes over the existing encoding schemes in discretization performance. This opens up possibilities of achieving much greater classification performance with high output entropy.
Index Terms:
pattern classification,biometrics (access control),cryptography,encoding,entropy,feature extraction,Gray codes,Hamming codes,cryptography,encoding scheme,effective biometric discretization,code separability,Hamming-distance separation,codewords,multibit biometric discretization,quantization-interval labeling,distance dissimilarity preservation,feature component mapping,discrete space,Hamming space,binary reflected Gray code,BRGC encoding,interclass variation,discrete-to-binary mapping,classification performance,binary output entropy,full-ideal separability capability,near-ideal separability capability,partially linearly separable subcode,PLSSC,entropy-performance tradeoff,entropy-redundancy tradeoff,code length,discretization performance,Encoding,Hamming distance,Reflective binary codes,Entropy,Indexes,Quantization,Labeling,linearly separable subcode,Biometric discretization,quantization,encoding
Citation:
Meng-Hui Lim, A. B. J. Teoh, "A Novel Encoding Scheme for Effective Biometric Discretization: Linearly Separable Subcode," IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 35, no. 2, pp. 300-313, Feb. 2013, doi:10.1109/TPAMI.2012.122
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