Black is black

If you thought that black is black, then think again. A team Iranian scientists has prepared 624 samples of black paper and fabrics to prepare a scale of blackness based on their reflectance spectra, as reported previously by the same team for white samples. As described in Color Research & Application, woven cotton samples were coloured with various commerical dyes in different mixtures and concentrations to produce a total of 457 black fabrics. In addition, 167 paper samples having different shades of black were prepared.

The reflectance spectra were processed by principal components analysis using the reflectance spectra, the Kubelka-Munk function of reflectance, and the inverse of reflectance factor to confirm that blacks can be described in 3D space, with 1D and 2D space being adequate in some cases.