Object Color Changes under Various Daylights

- Bases for the Corresponding Color Reproduction -

Abstract

This paper describes object color changes under various daylights. The changes were estimated by numerical experiments using Standard Object Colour Spectra Database (SOCS). First we found that, when we estimate the color under the second illumination with a correlated color temperature T' from the color under the first illumination with another correlated color temperature T using object spectral reflectance estimation, the estimated color is very stable independent of metamers. This fact allows us to define the incomplete chromatic adaptation in terms of the correlated color temperature of daylights. Second, we found that the incomplete chromatic adaptation can be symmetrically expressed using a quantity M whose unit is mired (micro reciprocal degree). These results could be the bases for a theory of corresponding color reproduction under different daylights.