In fluorescence spectroscopy the wavelength spectrum of fluorescence excitation and emission can be used to identify the fluorophore. In other words, each different material has a characteristic fluorescence spectrum, which is dependent on its chemical characteristics, and not e.g. on its reflectance spectrum or color.

Consequently, it is in principle possible to distinguish different materials when observing under UV light, even when they present the same color in day light conditions.

Moreover, by comparing known fluorescence emission of certain materials with the painting fluorescence image, it is in principle possible to classify the image and locate the different materials on the painting surface.