The colour of light depends on the subjective senses, similar to our perception of sound, smell, taste and touch.
Those senses are the result of stimuli acting on the sense organs and affecting the receptors. The receptors generate nerve impulses producing a specific sensation in the brain. The sensation of colours can be percepted by stimulating the photoreceptors at a specific optical wavelength.
This perception is directly related to the colour temperature, expressed in degrees Kelvin [K], defining the colour of the light source.
Classification of the colour temperature and corresponding colour perception:
2700 K - very warm
3000 K - warm
4000 K - neutral
6000 K and above
6000 K and more - cool
The colour perception depends on three key factors: hue, saturation and brightness.
a - Brightness
b - Saturation
Hue – is the perception of a specific optical wavelength. The senses can be described by referring to the subsequent wavelengths as violet, blue, green, yellow, orange and red.
Saturation – with more white light added to a certain wavelength, it does not change in hue but becomes more pale.
Brightness – to bring out a change in colour perception, a luminous flux can also be reduced, e.g. by increasing the distance between the light source from and the observed surface. It will not affect its hue or saturation, but will result in a weaker illumination. That is the brightness.