Fuzzy logic: a technique to Raman spectra recognition

This paper presents two strategies based on fuzzy logic to identify unknown Raman spectra. Following the guidelines of visual inspection, it would be possible to compare the whole spectrum of the analyzed sample with the spectra of standard materials or, once the wavenumber positions of the bands of the unknown spectrum are localized, to compare them with those of the reference spectra. In both cases, it is necessary to have a database in which either the whole standard spectrum or the position of their bands are stored. In order to automate and to facilitate the task of comparison and identification of Raman spectra, two fuzzy logic systems are proposed. In one case, the designed fuzzy logic system uses a similarity index that quantifies the likeness between the compared spectra to find out to which material can the unknown spectrum correspond. In the other case, the proposed fuzzy logic system identifies the analyzed material, searching for the coincidence on the position of their bands with those of the considered standard materials. In both cases, the identification of artistic pigments can be achieved from their Raman spectra in a systematic and objective way.