Colour and the eye
Beginner
Cones in the retina detect red, green, blue.
Three cone types (red, green, blue sensitive) give colour vision; all other colours are combinations of their responses. Colour blindness arises from missing or shifted cones.
Yellow light stimulates red and green cones.
Colour is a perception, not a property of the light alone.
In more detail
The human eye detects colour using three types of cone cells sensitive to different wavelength ranges. The brain combines their signals to perceive colour.
Real-world uses
- Colour displays exploit three cone types by using red, green and blue.
- Colour blindness results from missing or altered cone types.
- Screens show full colour because the eye has three types of cone cells sensitive to red, green and blue.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
Why do we see colour?
Different cones respond differently to light wavelengths, and the brain interprets the mix.
What is colour blindness?
A reduced ability to distinguish certain colours, usually caused by genetic changes in cone pigments.
Why do some people see colours differently?
Colour vision depends on the cone cells, and variations or deficiencies in them lead to colour blindness.
Related topics in Optics
Fermat's principle · Fresnel and Fraunhofer diffraction · Fibre optics numerical aperture · Additive and subtractive colour mixing · Photometry · Geometrical vs wave optics