Most of the visual stimuli for humans are illuminated objects reflecting to our eyes a fraction of the light impinging on them. Consequently, the color perception of complex scenes is influenced, among other factors, by the spectrum of the illumination (Shevell & Kingdom,
2008). Natural daylight is variable both spectrally and in intensity, e.g., during the day or at different locations (Hernández-Andrés, Romero, & Lee,
2001; Hernández-Andrés, Romero, Nieves, & Lee,
2001; Judd et al.,
1964); artificial illumination may vary even more dramatically, e.g., from incandescent to discharge lamps (
CIE, 2004; Thornton,
1973). Nevertheless, the visual system has the ability to compensate to some extent for these variations and to recover object colors reliably under natural illumination (Granzier, Brenner, & Smeets,
2009) and under artificial ones (Olkkonen, Hansen, & Gegenfurtner,
2009) almost with constant colors. Color constancy is, however, not perfect (Foster,
2003,
2011), and the effects of different lighting on the color and conspicuity of objects can be quite large and are typically addressed in color rendering (Schanda,
2007).