1. A method of determining a reflectance spectrum, comprising: obtaining a normalized value from a plurality of illuminant sensor outputs, each illuminant sensor output indicating a reflectance value obtained from a target; obtaining reference data from a reference database that correlates reference spectra with a corresponding plurality of normalized illuminant sensor outputs for reference colors, the reference data including data in a neighborhood of each reflectance value; and determining a spectrum &Scirc; based on the illuminant sensor outputs and the reference data, wherein the determining step places greater importance on the data in the neighborhood of each reflectance value.