Adaptation is the ability of the human eye to adjust to average Luminance in the field of vision. The human eye is capable of adapting within a luminance range of 10^-6 cd/m² to about 10^5 cd/m².

If the field of vision includes significant areas of pronounced luminance contrast, a process of continual re-adaptation takes place, which can soon cause fatigue. A lighting system offering optimum conditions for both visual perception and subjective well-being must therefore create a balanced distribution of luminance with the support of the appropriate choice of furnishings for the interior (cf. Contrast).