Chromatic adaptation and the relationship between lamp spectrum and brightness

Abstract

Previous research has examined the effect of the spectral power distribution of a light source upon the perception of interior spaces, noting that this can significantly affect brightness. It is expected that the impact of lamp spectrum on the brightness-illuminance relationship in these tests would be affected by chromatic adaptation. Three methods for assessing brightness were examined: side-by-side; rapid sequential; and individual presentation. The effect of lamp spectrum on brightness is attenuated with greater chromatic adaptation but it is not eliminated for every lamp comparison even after long-term adaptation. Thus to determine whether the effect of lamp spectrum on brightness is significant for the occupants of a building the lighting designer must question whether the occupant’s first impression or long-term impression of the lighting is more important.