Scotopic vision

[4] Under scotopic conditions, light incident on the retina is not encoded in terms of the spectral power distribution.

This dominance is due to the increased sensitivity of the photopigment molecule expressed in rods, as opposed to those in cones.

The elephant hawk-moth (Deilephila elpenor) displays advanced color discrimination even in dim starlight.

The normal human observer's relative wavelength sensitivity will not change due to background illumination under scotopic vision.

The principle that the wavelength sensitivity does not change during scotopic vision led to the ability to detect two functional cone classes in individuals.

Therefore, this photopigment only maps the rate of absorption and does not encode information about the relative spectral composition of the light.

For adaption to occur at very low levels, the human eye needs to have a large sample of light across the signal in order to get a reliable image.