Influence of ambient illumination on adapted and optimal white point

This study investigated the effect of the chromaticity and intensity of the ambient illumination on the adapted white point of a homogeneous image (i.e. the chromaticity that is perceived as achromatic) and on the optimal white point of natural images (i.e. the white point with the most preferred color rendering). It was found that the adapted white point and the optimal white point shift towards the chromaticity of the ambient illumination. The effect of illuminant color was approximately 2.5 times larger for the adapted white point than for the optimal white point. The intensity of the ambient illumination had no effect on the adapted white point and the optimal white point, except for images with face content. In agreement with previous studies, the optimal white point was found to strongly depend on image content. The results indicate that the optimal color rendering of natural images is a complex relation of image content and ambient illumination