Lighting Design Glossary

Photopic Vision

(Term of physiology)

Photopic vision is the scientific term for human color vision under normal lighting conditions during the day.

In the range above 3.4 cd/m², the human eye uses three types of cones to sense light in three respective bands of color. The pigments of the cones have maximum absorption values at wavelengths of about 445 nm (blue), 535 nm (green), resp. 575 nm (red). Their sensitivity ranges overlap to provide continuous (but not linear) vision throughout the visual spectrum. The maximum efficacy is 683 lumens/W at a wavelength of 555 nm (yellow).

In the range below 0.034 cd/m², the human eye usess scotopic vision. In the intermediate range, mesopic vision combines both types.