In agreement with the principles of the relativistic model proposed by
Creutzfeldt et al., with the photometric rule (lightness anchoring ru
le) and with the influence of simultaneous contrast in the appearance
of a visual scene, we propose a first-stage mechanism yielding substan
tial colour constancy. We have defined a set of first-stage colour des
criptors, and to test their utility, we have performed a simulation us
ing a Machine Vision System (MVS). The statistical stability of the de
scriptors for Munsell samples under different illuminants is good. (C)
1997 Elsevier Science Ltd.