by A.S. Charles, B.A. Olshausen and C.J. Rozell
Abstract:
The spectral features in hyperspectral imagery (HSI) contain significant structure that, if properly characterized could enable more efficient data acquisition and improved data analysis. Because most pixels contain reflectances of just a few materials, we propose that a \emphsparse coding model is well-matched to HSI data. Sparsity models consider each pixel as a combination of just a few elements from a larger dictionary, and this approach has proven effective in a wide range of applications. Furthermore, previous work has shown that optimal sparse coding dictionaries can be learned from a dataset with no other \empha priori information (in contrast to many HSI "endmember" discovery algorithms that assume the presence of pure spectra or side information). We modified an existing unsupervised learning approach and applied it to HSI data (with significant ground truth labeling) to learn an optimal sparse coding dictionary. Using this learned dictionary, we demonstrate three main findings: i) the sparse coding model learns spectral signatures of materials in the scene and locally approximates nonlinear manifolds for individual materials, ii) this learned dictionary can be used to infer HSI-resolution data with very high accuracy from simulated imagery collected at multispectral-level resolution, and iii) this learned dictionary improves the performance of a supervised classification algorithm, both in terms of the classifier complexity and generalization from very small training sets.
Reference:
Learning Sparse Codes for Hyperspectral ImageryA.S. Charles, B.A. Olshausen and C.J. Rozell. IEEE Journal of Selected Topics in Signal Processing, 5(5), pp. 963–978, September 2011.
Bibtex Entry:
@Article{charles.11c,
author = {Charles, A.S. and Olshausen, B.A. and Rozell, C.J.},
title = {Learning Sparse Codes for Hyperspectral Imagery},
year = {2011},
journal = {IEEE Journal of Selected Topics in Signal Processing},
abstract = {The spectral features in hyperspectral imagery (HSI) contain significant structure that, if properly characterized could enable more efficient data acquisition and improved data analysis. Because most pixels contain reflectances of just a few materials, we propose that a \emph{sparse coding} model is well-matched to HSI data. Sparsity models consider each pixel as a combination of just a few elements from a larger dictionary, and this approach has proven effective in a wide range of applications. Furthermore, previous work has shown that optimal sparse coding dictionaries can be learned from a dataset with no other \emph{a priori} information (in contrast to many HSI ``endmember'' discovery algorithms that assume the presence of pure spectra or side information).
We modified an existing unsupervised learning approach and applied it to HSI data (with significant ground truth labeling) to learn an optimal sparse coding dictionary. Using this learned dictionary, we demonstrate three main findings: i) the sparse coding model learns spectral signatures of materials in the scene and locally approximates nonlinear manifolds for individual materials, ii) this learned dictionary can be used to infer HSI-resolution data with very high accuracy from simulated imagery collected at multispectral-level resolution, and iii) this learned dictionary improves the performance of a supervised classification algorithm, both in terms of the classifier complexity and generalization from very small training sets.
},
month = sep,
volume = {5},
number = {5},
pages = {963--978},
url = {http://siplab.gatech.edu/pubs/charlesJSTSP2011.pdf}
}