Dictionary of light, colour & vision

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 page in the DICTIONARY and starts with a DEFINITION. Bullet ...
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Absorption

When light strikes an object, some wavelengths are absorbed and their energy is converted to heat, others undergo reflection or transmission. About absorption When light is absorbed by an object or medium, its energy is transferred to electrons and emitted ...
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Accommodation

Accommodation refers to the way our eyes keep things in focus by simultaneously changing the shape of each lens. The result is sharp images of the world regardless of whether things are close by or in the distance. About accommodation ...
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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 hue or saturation. About achromatic colours Near-neutral colours (very light ...
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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 array of hues an observer sees on the screens of ...
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Additive colour

Additive colour refers to the way any two or more wavelengths of light can be combined to produce other colours.  The RGB colour model, HSB colour model and Spectral colour model use different methods to produce systematic ranges of colour ...
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Adobe RGB colour space

The aim of a colour space is to ensure that a colour produced by a colour model is accurately reproduced when displayed on-screen, printed or made into paint. The Adobe RGB (1998) colour space is an RGB colour space developed ...
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Amacrine cells

Amacrine cells are interneurons in the human retina that interact with retinal ganglion cells and/or bipolar cells. About amacrine cells Amacrine cells are a type of interneuron within the human retina. Amacrine cells are embedded in the retinal circuitry. Amacrine ...
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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 a trough. In the case of an electromagnetic wave, amplitude ...
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Amplitude

The amplitude of an electromagnetic wave is a measurement of the distance from the centre line (or the still position) to the top of a crest or to the bottom of a corresponding trough. The greater the distance the more ...
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Analogous colours

Analogous colours are colours that are very similar to one another and appear next to each other on a colour wheel. About analogous colours Analogous colours are colours of similar hue. An example of a set of analogous colours is ...
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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 called the normal. In optics, the normal is a line drawn ...
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Angle of incidence

The angle of incidence measures the angle at which incoming light strikes a surface. About the angle of incidence The angle of incidence is measured between a ray of incoming light and an imaginary line called the normal. In optics, ...
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Angle of reflection

The angle of reflection measures the angle at which reflected light bounces off a surface. The angle of reflection is measured between a ray of light which has been reflected off a surface and an imaginary line called the normal ...
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Angle of reflection

The angle of reflection measures the angle at which reflected light bounces off a surface. About the angle of reflection The angle of reflection is measured between a ray of light which has been reflected off a surface and an ...
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Angle of refraction

The angle of refraction measures the angle to which light bends as it passes across the boundary between different media. The angle of refraction is measured between a ray of light and an imaginary line called the normal. In optics, ...
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Angle of refraction

The angle of refraction measures the angle to which light bends as it passes across the boundary between different media. About the angle of refraction The angle of refraction is measured between a ray of light and an imaginary line ...
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Atom

An atom is the smallest particle that can be described as a chemical. About atoms At the centre of an atom is a nucleus containing protons which are positively charged sub-atomic particles. The number of protons determines the chemical element ...
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Attributes of visual perception

Attributes of visual perception are the innate abilities, and the skills we develop over the course of a lifetime, that enable us to make sense of what we see. They are evident in the diverse properties of the world we ...
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Aurora

Aurora (also known as the polar lights) are a natural display of curtains, rays, spirals, and flickering patterns of light in the northern polar latitudes (Aurora Borealis) and southern polar latitudes (Aurora Australis). They are most prominent after dark. About ...
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