18. The method as recited in claim 17 , wherein said simultaneous sparse approximation is of a greedy adaptive decomposition (GAD) type, said candidate spectral components being established within the general dictionary, said candidate spectral components each being defined either as a continuous function or as a discrete vector.
28. The method as recited in claim 18 , wherein said discovery processing includes hypothesis testing for adjustably optimizing said core spectral signatures with respect to predetermined statistical criteria.