Spectral-reflectance function recovery for improved colour-constancy experiments

A set of symmetric memory-matching data is presented to analyse some implications of long-term memory factors within classical colourconstancy paradigms and separation algorithms. Using simulated Mondrian-type colour surrounds on a CRT monitor, subjects make a series of colour matches between a test and a matching surface; the surfaces are rendered under the same standard illuminant (equal-energy illuminant). The 16 test surfaces used were categorised into four apparent-hue collections. The analysis of the colour differences show that subjects maintained good mental representations of the surfaces, although a shift in luminance was found. With these results, we investigated how errors in remembering surface colours might be translated into errors in reconstructing surface reflectances. Thus, a description of the remembered surfaces is provided, and the spectral differences are analysed via a goodness-of-fit coefficient (GFC). As it is derived from colour-differential thresholds and GFC values, the analysis of the recalled spectral-reflectance functions shows little loss of information in the observer’s task, despite imperfect mathematical recovery of the surfaces. The similarities between test and matching surfaces suggest that colour-constancy algorithms could benefit of memory matches when an illuminant change takes place, and use spectral-tolerance bands defined over the surfaces comprising a scene to improve their implementation. q 2002 Elsevier Science B.V. All rights reserved.