Applying chromatic adaptation transforms to mixed adaptation conditions

Abstract

AbstractA set of psychophysical experiments was conducted to investigate the state of adaptation between hardcopy and softcopy images when viewed under mixed illumination conditions. The performance of three chromatic adaptation transforms, CMCCAT97, CMCCAT2000 and CIECAT94, was compared to that of the S‐LMS, a mixed adaptation model. The adaptation ratios of each model were varied to investigate the state of adaptation of the human visual system. Printed complex images were used as originals. A series of softcopy reproduction pairs was displayed on a CRT with a D93 white point and compared to the original in an illuminated room. Three ambient lights were studied: a D50 simulator, an Illuminant A simulator and a Cool‐white fluorescence lamp. The experiments were divided into nine phases according to the changes of illuminants and the luminance levels. A simultaneous binocular matching technique was employed. Observers compared the hardcopy with a given pair of softcopies and identified which reproduction was the closer colour match. The results showed that the state of adaptation of the human visual system was between 40–60% adapted to the white point of the monitor regardless of the changes in illumination conditions. The overall results showed that CMCCAT2000 with proper adaptation ratio outperformed the other models and could be applied to mixed adaptation conditions. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 436–444, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10196