This work presents the analysis of the deterministic part of human colour perception at the computational, algorithmic and implementation levels. At the computational and algorithmic levels, we invoke the theory of Fuzzy sets. At the implementation level, we present Biologically Inspired Photochromic Fuzzy Logic (BIPFUL) systems that are useful to discriminate between the three regions of the UV spectrum (UV-A, UV-B and UV-C). Such BIPFUL systems have been devised by imitation of the human photosensitive system on retina. After transforming the absorption spectra, originated by the BIPFUL systems under UV-A, UV-B and UV-C, in chromaticity coordinates and vectors in CIE L*a*b* spaces, we have compared their performances through the determination of two parameters: The Colourability and the Eucledian distance. Finally, the guiding principles for the design of new BIPFUL systems are outlined.