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Virtual Journal for Biomedical Optics

Virtual Journal for Biomedical Optics


  • Editor: Gregory W. Faris
  • Vol. 2, Iss. 8 — Aug. 10, 2007

Recovering fluorescent spectra with an RGB digital camera and color filters using different matrix factorizations

Juan L. Nieves, Eva M. Valero, Javier Hernández-Andrés, and Javier Romero  »View Author Affiliations

Applied Optics, Vol. 46, Issue 19, pp. 4144-4154 (2007)

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The aim of a multispectral system is to recover a spectral function at each image pixel, but when a scene is digitally imaged under a light of unknown spectral power distribution (SPD), the image pixels give incomplete information about the spectral reflectances of objects in the scene. We have analyzed how accurately the spectra of artificial fluorescent light sources can be recovered with a digital CCD camera. The red-green-blue (RGB) sensor outputs are modified by the use of successive cutoff color filters. Four algorithms for simplifying the spectra datasets are used: nonnegative matrix factorization (NMF), independent component analysis (ICA), a direct pseudoinverse method, and principal component analysis (PCA). The algorithms are tested using both simulated data and data from a real RGB digital camera. The methods are compared in terms of the minimum rank of factorization and the number of sensors required to derive acceptable spectral and colorimetric SPD estimations; the PCA results are also given for the sake of comparison. The results show that all the algorithms surpass the PCA when a reduced number of sensors is used. The experimental results suggest a significant loss of quality when more than one color filter is used, which agrees with the previous results for reflectances. Nevertheless, an RGB digital camera with or without a prefilter is found to provide good spectral and colorimetric recovery of indoor fluorescent lighting and can be used for color correction without the need of a telespectroradiometer.

© 2007 Optical Society of America

OCIS Codes
(150.0150) Machine vision : Machine vision
(150.2950) Machine vision : Illumination
(330.1710) Vision, color, and visual optics : Color, measurement
(330.1730) Vision, color, and visual optics : Colorimetry

ToC Category:
Vision and color

Original Manuscript: November 20, 2006
Revised Manuscript: February 26, 2007
Manuscript Accepted: March 1, 2007
Published: June 12, 2007

Virtual Issues
Vol. 2, Iss. 8 Virtual Journal for Biomedical Optics

Juan L. Nieves, Eva M. Valero, Javier Hernández-Andrés, and Javier Romero, "Recovering fluorescent spectra with an RGB digital camera and color filters using different matrix factorizations," Appl. Opt. 46, 4144-4154 (2007)

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