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.
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. 23. The method as recited in claim 18 , further comprising the step of maintaining a spectral signature dictionary updated responsive to said discovery processing to store said core spectral signatures discovered thereby.