Archives: Knowledge Base

A surface that reflects sunlight . . . without absorbing any of its colors is said to be white.

A surface that reflects sunlight . . . without absorbing any of its colors is said to be white. A surface that absorbs all colors, reflecting none, is said to be black. Weak vibrations of white light result in the ...
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Absorption

When light strikes an opaque material the wavelengths that are not reflected are absorbed and their energy is converted to heat (notice that absorption has a 'p'). When sunlight strikes an opaque object or material, it can be reflected or absorbed ...
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Accommodation

Accommodation refers to the way the eye increases optical power by changing the shape of the lens. This is necessary to produce a clear, focused, image of an object when it is near to the eye. The eye focuses on a given object ...
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Achromatic

Any colour that lacks strong chromatic content is said to be achromatic, unsaturated, or near neutral. Pure achromatic colours include black, white and all greys. Achromatic, unsaturated colours include browns, tans, pastels and darker colours. Achromatic, unsaturated colours can be ...
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Additive colour

Additive colour involves mixing different wavelengths of light to produce other colours. Whilst additive colour is the method used to mix wavelengths of light, subtractive colour is the method used to mix dyes, inks and paints. An additive approach to ...
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Additive colour

Additive colour is a method of mixing different wavelengths of light to produce other colours. An additive approach to colour is used in the case of emission of light from the screens of mobile phones, computers and televisions. An additive ...
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Adobe RGB colour space

The Adobe RGB (1998) colour space is an RGB colour space developed by Adobe Systems, Inc. Adobe RGB (1998) colour space was designed to encompass most of the colours achievable on CMYK colour printers. By using RGB primary colours on ...
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AI (Adobe Illustrator) file format

Download the image at the top of this page as an AI (Adobe Illustrator) file: All AI images available for download from lightcolourvision.org are 1686px wide. All the images on these Resource Pages were created in Adobe Illustrator and are ...
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Amacrine cell

Amacrine cells are interneurons in the human retina that interact with retinal ganglion cells and/or bipolar cells. Amacrine cells interact with bipolar cells and/or ganglion cells. They are another type of interneuron which in this case monitor and augment the ...
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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 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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Analogous colours

Analogous colours are groups of colours that are adjacent to each other on a colour wheel, with one being the dominant colour. The dominant colour amongst a group of analogous colours is usually a primary or secondary colour. The immediately adjacent colours to secondary ...
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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. 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 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. 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 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. The angle of refraction is measured between a ray of light and an imaginary line called the normal. In optics, ...
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Article 2A-2

A starting point As a living, conscious human being I must struggle to make sense of the world. It often feels as if there is so much more than I understand and that I understand only a small part of ...
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Atom

An atom is the smallest particle that can be described as a chemical. At the centre of an atom is a nucleus containing protons which are positively charged sub-atomic particles. The number of protons determines what chemical the atom is ...
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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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Bands of colour

An observer perceives bands of colour because: The human eye is able to distinguish between some ranges of wavelengths of visible light better than others. Some ranges of wavelengths appear more intense to a human observer than others. Colour is ...
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Bands of colour

An observer perceives bands of colour because: The human eye is able to distinguish between some ranges of wavelengths of visible light better than others. Some ranges of wavelengths appear more intense to a human observer than others. Colour is ...
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Bipolar cells

Bipolar cells are a type of neuron found in the retina of the human eye. They are located between photoreceptors (rod cells and cone cells) and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells. Bipolar cells are ...
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Black body

An object that absorbs all radiation falling on it, at all wavelengths, is called a black body. A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. When a black body (at a uniform temperature), emits radiation (visible light, infrared light, ultraviolet ...
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Brightness

The brightness (luminance, brilliance) of an object refers to the quality, apart from hue and saturation that an observer uses to determine the comparative brightness of another object. In terms of tonal differences, pure white has the maximum brightness, and ...
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Checking the author !!

Remember !! If the quote (or other material) you found is signed off by Imagewheel then use the information on this page. Otherwise credit the original author in your in-line citation and reference ...
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Chemical bond

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. A chemical compound consists of two or more atoms from different elements chemically bonded together. There are two types of chemical bond: covalent bonds and ionic bonds: A covalent bond forms when two ...
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Color can only exist when three components are present

Color can only exist when three components are present: a viewer, an object, and light. Although pure white light is perceived as colorless, it actually contains all colors in the visible spectrum. When white light hits an object, it selectively ...
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Color is a property of light that depends on wavelength

Color is a property of light that depends on wavelength. When light falls on an object, some of it is absorbed and some is reflected (Columbia Encyclopedia, 2016) ...
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Color is the perception of reflected light

Color is the perception of reflected light, expressed as hue, lightness, and saturation.  It is the visual sensation which helps one differentiate between otherwise similar objects.  Hue is the gradation between colors which allows them to be classified as Red, ...
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Colour

Things appear coloured because colour corresponds with a property of light that is visible to the human eye. The visual experience of colour is associated with words such as red, blue, yellow, etc. The colour an observer sees depends on: ...
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Colour

Things appear coloured because colour corresponds with a property of light that is visible to the human eye. The visual experience of colour is associated with words such as red, blue, yellow, etc. The experience of colour is a feature ...
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Colour constancy

Colour constancy refers to the ability of the human eye and brain to automatically compensate when objects change colour because of changes in illumination. Colour vision relies on colour constancy to enable an observer to perceive the colour of an ...
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Colour model

A colour model is a method for mixing colours Light of different wavelkengths (and so different colours) Powder paints Acrilic paints Industrial paints A colour model is A basic RGB colour model does not define the precise wavelengths of the ...
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Colour notation

The most common forms of colour notation used with computer software and by digital equipment are the triplets of the  RGB and HSB colour models and the quadruplets used by CMYK model. RGB notation can be represented in decimal or ...
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Colour of objects

A material gets its colour as electrons absorb some wavelengths of light and reflect others. The colour an observer sees corresponds with the reflected wavelengths. Three key factors affect the colour of an object. The light source and what happens ...
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Colour of objects

A material gets its colour as electrons absorb some wavelengths of light and reflect others. The colour an observer sees corresponds with the reflected wavelengths ...
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Colour vision

Colour vision is the ability of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they emit, reflect or transmit. The human eye and brain together translate light into colour. The human eye, ...
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Colour vision

Colour vision is the ability of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they emit, reflect or transmit. The human eye and brain together translate light into colour. The human eye, ...
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Colour wheel

A colour wheel is a diagram based on a circle divided into segments. The minimum number of segments is three with a primary colour in each. Segments added between the primaries can then be used to explore the result of ...
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Colour wheel

A colour wheel is a diagram based on a circle divided into segments. The minimum number of segments is three with a primary colour in each. Segments added between the primaries can then be used to explore the result of ...
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Colours are seen when sources of light emit . . . parts of the full visible spectrum

The website of Prof. Dr. Dietrich Zawischa asks a central question, what are the causes of colour (Zawischa, 2013)?  He suggests that any sensation of colour can be attributed to one of the three categories ...
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Complementary

In the context of a discussion of light (as opposed to pigments) complementary colours are two colours that, when mixed together, produce white light. When working with the RGB colour model, combining the wavelengths corresponding with red, green and blue ...
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Compound

A compound is a substance made from the combination of two or more elements and held together by chemical bonds that are difficult to break. The bonds form as a result of sharing or exchanging electrons among atoms. The smallest ...
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Cone cell

Cone cells, or cones, are one of three types of photoreceptor cells (neurons) in the retina of the human eye. They are responsible for colour vision and function best in relatively bright light, as opposed to rod cells, which work ...
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Cone cell

Cone cells, or cones, are one of three types of photoreceptor cells (neurons) in the retina of the human eye. They are responsible for colour vision and function best in relatively bright light, as opposed to rod cells, which work ...
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Continuous spectrum

A continuous spectrum, emitted by a light source such as the sun, consists of a continuum of wavelengths of electromagnetic radiation across the visible spectrum. A continuous spectrum is produced by light emitted by excited atoms. It results from free ...
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Crest

The crest is the point on a wave with the maximum value of upward displacement within a wave-cycle. A trough is the opposite of a crest, so the minimum or lowest point in a wave-cycle. On a wave at sea, the crest is a point where the displacement ...
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Crest

The crest is the point on a wave with the maximum value of upward displacement within a wave-cycle ...
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