[1] Inst Telecomunicacoes, Lisbon, Portugal
[2] Inst Super Engn Lisboa, Lisbon, Portugal
[3] Univ Tech Lisbon, Inst Super Tecn, P-1100 Lisbon, Portugal
[4] Univ Extremadura, Hyperspectral Comp Lab, Caceres, Spain
[5] Univ Coimbra, Inst Telecommunicacoes, DEEC, P-3000 Coimbra, Portugal