Figure 1.

(a) Pattern 1 and pattern 2. (b) Reflectance spectrum of coloured (R, red; O, orange; P, purple; Gr, grey; Bk, black) papers. Numbers after the symbols indicate intensity: smaller numbers correspond to higher intensities. The insets of (i) and (ii) in (b), respectively, show the irradiation spectrum measured relative to an magnesium oxide-coated surface and the spectral sensitivities of six receptor classes.