Suchitra Sueeprasan

Modeling incomplete adaptation under mixed illuminants

Three chromatic adaptation transforms; CMCCAT97, CMCCAT2000 and CIECAT94, and the S-LMS mixed adaptation model were tested for cross-media colour reproduction under mixed illuminants. For each model, the adaptation ratio was varied to represent the state of adaptation. Printed complex images were used as originals. A series of softcopy reproduction pairs was displayed on a CRT with a D93 white point. Observers compared the hardcopy with a given pair of softcopies simultaneously and decide which reproduction was the closer color match. The experiments were divided into three phases according to the ambient lights in the experimental room. They varied from D50 simulators, Illuminant A and Cool-white Fluorescence at similar luminance level to that of the CRT. The results clearly showed that in most cases, the adaptation ratio of 0.4 was best for all models. It was also found that the adaptation ratio was not dependent on the color temperature of the ambient light and image content. The CMCCAT2000 performed relatively well in all cases.