COLOR CONSTANCY .1. BASIC THEORY OF 2-STAGE LINEAR RECOVERY OF SPECTRAL DESCRIPTIONS FOR LIGHTS AND SURFACES

Changing a scene's illuminant causes the chromatic properties of refle cted lights to change. This change in the lights from surfaces provide s spectral information about surface reflectances and illuminants. We examine conditions under which these properties may be recovered by us ing bilinear models. Necessary conditions that follow from comparing t he number of equations and the number of unknowns in the recovery proc edure are not sufficient for unique recovery. Necessary and sufficient conditions follow from demanding a one-to-one relationship between qu antum catch data and sets of lit surfaces. We present an algorithm for determining whether spectral descriptions of lights and surfaces can be recovered uniquely from reflected lights.