Dictionary of light, colour & vision

A rainbow is an optical effect

A rainbow is an optical effect, a trick of the light, caused by the behaviour of light waves travelling through transparent water droplets towards an observer. Sunlight and raindrops are ...

About this dictionary

This DICTIONARY OF LIGHT, COLOUR & VISION contains a vocabulary of closely interrelated terms that underpin all the resources you will find here at lightcolourvision.org. Each term has its own ...

Absorption

When light strikes an object, some wavelengths are absorbed and their energy is converted to heat, others undergo reflection or transmission. When light is absorbed by an object or medium, ...

Accommodation

Accommodation refers to the way our eyes keep things in focus by changing the shape of the lens in each eye. The result is sharp images of the world regardless ...

Accommodation

Accommodation The distance between the retina (the detector) and the cornea (the refractor) is fixed in the human eyeball. The eye must be able to alter the focal length of ...

Achromatic

Achromatic means without colour so refers to surfaces or objects that appear white, grey or black. Achromatic colours can be described in terms of their apparent brightness but are without ...

Additive colour

An additive approach to colour refers to a method of mixing different wavelengths of light to produce other colours. An additive approach to colour is used to produce the vast ...

Additive colour

Additive colour refers to the way any two or more wavelengths of light can be combined to produce another colour.  The RGB colour model, HSB colour model and Spectral colour ...

Adobe RGB colour space

The Adobe RGB (1998) colour space was developed by Adobe Systems. It aims to ensure the optimal range of colours available within the RGB colour model and the CMKY colour ...

Alexander’s band

Alexander's band (Alexander's dark band) is an optical effect associated with rainbows. The term refers to the area between primary and secondary bows that often appears to be noticeably darker ...

Alexander’s band

Alexander's band (Alexander's dark band) is an optical effect associated with rainbows. The term refers to the area between primary and secondary bows that often appears to be noticeably darker ...

Amacrine cells

Amacrine cells are interneurons in the human retina that interact with retinal ganglion cells and/or bipolar cells. Amacrine cells are a type of interneuron within the human retina. Amacrine cells ...

Amacrine cells

Amacrine cells Amacrine cells interact with bipolar cells and/or ganglion cells. They are a type of interneuron that monitor and augment the stream of data through bipolar cells and also ...

Amplitude

The amplitude of a wave is a measurement of the distance from the top of a crest through the centre line  (the still position, zero-point, mid-point) to the bottom of ...

Amplitude

The amplitude of an electromagnetic wave is directly connected with the amount of energy it carries. In a wave diagram, amplitude is shown as the distance from the centre line ...

Analogous colours

Analogous colours are colours that are very similar to one another and appear next to each other on a colour wheel. Analogous colours are colours of similar hue. An example ...

Angle of deflection

The angle of deflection measures the angle between the original path of a ray of incident light prior to striking a raindrop and the angle of deviation which measures the ...

Angle of deflection

When discussing the formation of rainbows, the angle of deflection measures the angle between the original path of an incident ray of light, prior to striking a raindrop, and the ...

Angle of deviation

(1) The angle of deviation measures the angle between the direction of an incident ray and the direction of a refracted ray when light travels from one medium to another ...

Angle of incidence

The angle of incidence measures the angle at which incoming light strikes a surface. The angle of incidence is measured between a ray of incoming light and an imaginary line ...