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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 11, Iss. 12 — Jun. 16, 2003
  • pp: 1462–1473

Optimal discrimination and classification of THz spectra in the wavelet domain

Roberto K. H. Galvão, Sillas Hadjiloucas, John W. Bowen, and Clarimar J. Coelho  »View Author Affiliations

Optics Express, Vol. 11, Issue 12, pp. 1462-1473 (2003)

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In rapid scan Fourier transform spectrometry, we show that the noise in the wavelet coefficients resulting from the filter bank decomposition of the complex insertion loss function is linearly related to the noise power in the sample interferogram by a noise amplification factor. By maximizing an objective function composed of the power of the wavelet coefficients divided by the noise amplification factor, optimal feature extraction in the wavelet domain is performed. The performance of a classifier based on the output of a filter bank is shown to be considerably better than that of an Euclidean distance classifier in the original spectral domain. An optimization procedure results in a further improvement of the wavelet classifier. The procedure is suitable for enhancing the contrast or classifying spectra acquired by either continuous wave or THz transient spectrometers as well as for increasing the dynamic range of THz imaging systems.

© 2003 Optical Society of America

OCIS Codes
(100.7410) Image processing : Wavelets
(170.1580) Medical optics and biotechnology : Chemometrics
(300.6270) Spectroscopy : Spectroscopy, far infrared
(300.6300) Spectroscopy : Spectroscopy, Fourier transforms
(320.7100) Ultrafast optics : Ultrafast measurements
(330.4270) Vision, color, and visual optics : Vision system neurophysiology
(330.6180) Vision, color, and visual optics : Spectral discrimination

ToC Category:
Research Papers

Original Manuscript: February 25, 2003
Revised Manuscript: June 2, 2003
Published: June 16, 2003

Roberto Galvão, Sillas Hadjiloucas, John Bowen, and Clarimar Coelho, "Optimal discrimination and classification of THz spectra in the wavelet domain," Opt. Express 11, 1462-1473 (2003)

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