Spectral encoding/decoding methods using unique base functions and physically meaningful values were explored. Three new methods such as, TrW6 consisting of six unique trigonometric functions, Lab2 consisting of two CIELAB functions, and LabRGB consisting of CIELAB and RGB, were derived and compared against the traditional eigenvectors method. It was found that TrW6 and LabRGB showed almost the same accuracy as the traditional eigenvector method. By using LabRGB, color characteristics can be estimated by only looking at its encoding values and we do not have to exchange base functions beforehand for exchanging a different population of object colors. LabRGB can be applied not only to spectral imaging but also to traditional trichromatic imaging world, so its use can extend beyond spectral uses.