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Journal of Electrical and Computer Engineering
Volume 2012 (2012), Article ID 850637, 8 pages
http://dx.doi.org/10.1155/2012/850637
Research Article

Spectral Distortion in Lossy Compression of Hyperspectral Data

1IFAC-CNR, Institute of Applied Physics “Nello Carrara”, National Research Council of Italy, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
2Department Electronics & Telecommunications, University of Florence, Via S. Marta 3, 50139 Florence, Italy

Received 1 August 2011; Accepted 25 October 2011

Academic Editor: Raffaele Vitulli

Copyright © 2012 Bruno Aiazzi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Distortion allocation varying with wavelength in lossy compression of hyperspectral imagery is investigated, with the aim of minimizing the spectral distortion between original and decompressed data. The absolute angular error, or spectral angle mapper (SAM), is used to quantify spectral distortion, while radiometric distortions are measured by maximum absolute deviation (MAD) for near-lossless methods, for example, differential pulse code modulation (DPCM), or mean-squared error (MSE) for lossy methods, for example, spectral decorrelation followed by JPEG 2000. Two strategies of interband distortion allocation are compared: given a target average bit rate, distortion may be set to be constant with wavelength. Otherwise, it may be allocated proportionally to the noise level of each band, according to the virtually lossless protocol. Comparisons with the uncompressed originals show that the average SAM of radiance spectra is minimized by constant distortion allocation to radiance data. However, variable distortion allocation according to the virtually lossless protocol yields significantly lower SAM in case of reflectance spectra obtained from compressed radiance data, if compared with the constant distortion allocation at the same compression ratio.