Photopic vision is the scientific term for human colour 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 colour. 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).

Scotopic vision is the scientific term for human vision "in the dark", below 0.034 lm/m².

In that range, the human eye uses rods to sense light. Since the rods have a single absorption maximum of about 1700 lumens/W at a wavelength of 507 nm, scotopic vision is colour blind. The sensitivity range of the rods makes the eye more sensitive to blue light at night, while red light is almost exclusively perceived through photopic vision.

In the range above 3.4 cd/m², the human eye uses photopic vision. In the

intermediate range, mesopic vision combines both types.