Publications

Journal papers

  1. P. V. Giampouras, A. A. Rontogiannis, K. E. Themelis, K. D. Koutroumbas, “Online sparse and low-rank subspace learning from incomplete data: A Bayesian view”, Signal Processing, vol. 137, pp. 199-212, Aug. 2017.

  2. P. V. Giampouras, K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Simultaneously sparse and low-rank abundance matrix estimation for hyperspectral image unmixing”, IEEE Transactions on Geoscience and Remote Sensing, vol. 54, no. 8, pp. 4775-4789, Aug. 2016.

  3. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Variational Bayes group sparse time-adaptive parameter estimation with either known or unknown sparsity pattern”, IEEE Transactions on Signal Processing, vol.64, no.12, pp.3194-3206, June 2016.

  4. A. Belehaki, I. Tsagouri, I. Kutiev, P. Marinov, B. Zolesi, M. Pietrella, K. E. Themelis, P. Elias, K. Tziotziou, “The European Ionosonde Service: nowcasting and forecasting ionospheric conditions over Europe for the ESA Space Situational Awareness services”, Journal of Space Weather and Space Climate, 5 A25, 2015.

  5. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “A variational Bayes framework for sparse adaptive estimation”, IEEE Transactions on Signal Processing, vol.62, no.18, pp.4723-4736, Sept. 2014. pdf, code.

  6. K. E. Themelis, F. Schmidt, O. Sykioti, A. A. Rontogiannis, K. D. Koutroumbas, I. A. Daglis, “On the Unmixing of MeX/OMEGA Hyperspectral Data”, Planetary and Space Science, Elsevier, vol. 68, issue 1, pp.34-41, Aug. 2012. pdf

  7. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “A Novel Hierarchical Bayesian Approach for Sparse Semi-Supervised Hyperspectral Unmixing”, IEEE Transactions on Signal Processing, vol. 60, no. 2, pp. 585-599, Feb. 2012. pdf code

Conference papers

  1. K. E. Themelis, F. Lanusse, N. Jeffrey, A. Peel, J.-L. Starck, and F. B. Abdalla, “Modelling Data with Both Sparsity and a Gaussian Random Field: Application to Dark Matter Mass Mapping in Cosmology,” in Proceedings of the 26th European Signal Processing Conference (EUSIPCO), Rome, Italy, September 3-7, 2018.

  2. K. E. Themelis, A. A. Rontogiannis, and K. D. Koutroumbas, “Online Bayesian group sparse parameter estimation using a Generalized Inverse Gaussian Markov chain”, in Proceedings of the 23th European Signal Processing Conference (EUSIPCO), Nice, France, Sep. 2015.

  3. P. V. Giampouras, A. A. Rontogiannis, K. E. Themelis and K. D. Koutroumbas, “Online Bayesian low-rank subspace learning from partial observations”, in Proceedings of the 23th European Signal Processing Conference (EUSIPCO), Nice, France, Sep. 2015.

  4. P. V. Giampouras, A. A. Rontogiannis, K. D. Koutroumbas and K. E. Themelis, “A sparse reduced-rank regression approach for hyperspectral image unmixing”, in Proceedings of the 3rd International Workshop on Compressed Sensing Theory and its Application to Radar,Sonar and Remote Sensing (CoSeRa), Pisa,Italy, June 2015.

  5. P. V. Giampouras, K. E. Themelis, A. A. Rontogiannis and K. D. Koutroumbas, “Hyperspectral image unmixing via silultaneously sparse and low rank abundance matrix estimation”, in Proceedings of the 7th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (IEEE WHISPERS), Tokyo, June 2015.

  6. G. Papageorgiou, P. Bouboulis, S. Theodroridis, K. E. Themelis, “Robust linear regression analysis - the greedy way”, in Proceedings of the 22th European Signal Processing Conference (EUSIPCO), Lisbon, Portugal, Sep. 2014.

  7. K. E. Themelis, A. A. Rontogiannis, and K. D. Koutroumbas, “Group-sparse adaptive variational Bayes estimation”, in Proceedings of the 22th European Signal Processing Conference (EUSIPCO), Lisbon, Portugal, Sep. 2014.

  8. P. V. Giampouras, K. E. Themelis, A. A. Rontogiannis, and K. D. Koutroumbas, “A variational Bayes algorithm for joint-sparse abundance estimation”, in Proceedings of the 6th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (IEEE WHISPERS), Lausanne, June 2014. pdf

  9. K. E. Themelis, A. A. Rontogiannis, and K. D. Koutroumbas,“Adaptive variational sparse Bayesian estimation,” Acoustics, Speech and Signal Processing (ICASSP), IEEE International Conference on, Florence, Italy, May 2014.

  10. K. E. Themelis, A. A. Rontogiannis, and K. D. Koutroumbas,“Variational Bayesian sparse adaptive filtering using a Gauss-Seidel recursive approach,” in Proceedings of the 21th European Signal Processing Conference (EUSIPCO), Marocco, Sep. 2013.

  11. A. A. Rontogiannis, K. E. Themelis, O. Sykioti and K. D. Koutroumbas, “A fast variational Bayes algorithm for sparse semi-supervised unmixing of OMEGA/Mars data”, in Proceedings of the 5th Workshop on Hyperspectral Image and Signal Processing: Evolution in Remote Sensing (IEEE WHISPERS), Florida, June 2013.

  12. A. A. Rontogiannis, K. E. Themelis, K. D. Koutroumbas, “A Fast Algorithm for the Bayesian Adaptive Lasso”, in Proceedings of the 20th European Signal Processing Conference (EUSIPCO), Bucharest, Sep. 2012.

  13. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Sparse Semi-Supervised Hyperspectral Unmixing Using a Novel Iterative Bayesian Inference Algorithm”, in Proceedings of the 19th European Signal Processing Conference, Barcelona, Sep. 2011.

  14. K. E. Themelis, A. A. Rontogiannis, O. Sykioti, K. D. Koutroumbas, I. A. Daglis, F. Schmidt, “On the Unmixing of MEx/OMEGA Hyperspectral Data”, In Proceeding of the European Planetary Science Congress (EPSC) , Rome, Sep. 2010.

  15. K. E. Themelis, A. A. Rontogiannis, O. Sykioti, K. D. Koutroumbas, I. A. Daglis, F. Schmidt, “On the unmixing of MEx/OMEGA hyperspectral data using a MAP Estimator”, Geophysical Research Abstracts, 12, PS7.1 Spectroscopy and radiative transfer in Planetary atmospheres, EGU General Assembly, Vienna, April 2010.

  16. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Semi-Supervised Hyperspectral Unmixing via the Weighted Lasso”, in Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Dallas, TX, March 2010. pdf code

  17. K. E. Themelis, A. A. Rontogiannis, “A Soft Constrained MAP Estimator for Supervised Hyperspectral Signal Unmixing”, in Proceedings of the 16th European Signal Processing Conference (EUSIPCO), Lausanne, Aug. 2008.

  18. G. Anogianakis, E. Kapritsos, C. Makris, N. Mpaltas, K.E. Themelis , K. Perdikuri, A. Tsakalidis, “Idenitification of protein patterns in nucleic acid sequences and exploration of synonymous codons in tissue differentiation”, Computational Biology and Genome Information Conference, 2005.

Book chapters

  1. P.V Giampouras, K.E. Themelis, A.A. Rontogiannis, K.D. Koutroumbas, “Structured Abundance Matrix Estimation for Land Cover Hyperspectral Image Unmixing”, Chapter in book: Compressive Sensing of Earth Observations, C.H. Chen (Editor), CRC Press Signal and Image Processing of Earth Observations Book Series, 2017.

Technical reports

  1. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Semisupervised hyperspectral image unmixing using a variational Bayes algorithm”, technical report, National Observatory of Athens, June, 2014. pdf code

  2. K. E. Themelis, A. A. Rontogiannis, K. D. Koutroumbas, “Spectral unmixing algorithms”, technical report, National Observatory of Athens, July, 2013. pdf

  3. K. E. Themelis, “Bayesian signal processing techniques for hyperspectral image unmixing”, technical report, University of Athens, December, 2012. pdf

Ph.D. thesis