Explanations of terms relating to the Natural Colour SystemDelta E is a numerical value calculated from colour measurements. The value was scaled so that 1 unit approximately should correspond to the largest acceptable colour difference in commercial matters.
Achromatic colours - black, white and the greys - are colours that are devoid of any chromaticness.
Blueness is a colour's resemblance to the elementary colour blue.
Chromatic means that a colour corresponds to a hue. The chromatic elementary colours of the NCS System are yellow, red, blue and green.
CIE is an abbreviation of Commission Internationale d'Eclairage, the international body for colorimetry (measurement of colour).
CIELAB is a system that is used to define total colour difference by combining three independent variables based on the three opponent pairs of colour vision: white-black, red-green, and yellow-blue.
CMYK stands for Cyan, Magenta, Yellow and Black and is the colour breakdown used for four colour process printing.
Elementary Colours of the NCS System are yellow, red, blue, green, white and black. All other colours within the NCS System can be described in terms of these colours.
Gloss Level is measured according to ISO 2813, 60°. Gloss level instruments illuminate the surface at a 60° angle and measure the reflected fraction of the light. The minimum gloss level is 0 and corresponds to a completely matt surface and the maximum is 100 gloss units corresponding to a very glossy surface.
Glossy A high gloss version of the collection of the 1950 NCS colours. NCS Glossy has a gloss level of approximately 85 units. The normal gloss level of NCS products is 15-20 units.
Greenness is a colour's resemblance to the elementary colour green.
Hue describes the relative amount of the two nearest chromatic elementary colours that the colour is perceived to contain.
ISO is an abbreviation of International Standards Organisation.
|Lightness of a coloured material can be determined either by instrumental measurement of LRV - light reflectance value, or by comparison with samples having known lightness values, e.g. the NCS Lightness Meter, which is a grey scale. Colours with the same lightness are found along the straight lines of the diagram. The positioning of these lines will vary for different hues.|
LRV - Light Reflectance Valueis an instrumental measurement made using a spectrophotometer. It is equivalent to CIE Y and is the proportion of visible light reflected by a surface, weighted for the sensitivity to light of the human eye.
LRV is expressed on a scale of 0-100 where absolute white has a value of 100 and absolute black has a value of 0. In practice white may be about 85 and black about 6.
For people with adequate vision, difference in hue or chroma (colour intensity) provide sufficient visual contrast. But for people who are visually impaired the main feature of a surface which determines the ability to identify differences in colour is the amount of light the surface reflects, or its LRV. LRVs for all 1,950 NCS colours can be obtained by using the NCS Colour Scan.
Metamerism is present when two objects look the same colour under one light source, but different under another light source. This is due to the objects reflecting different wavelengths under each light source. This effect often occurs with fabrics.
NCS is an abbreviation of Natural Colour System, which is based on the way that humans perceive colour.
Opponent Colour Theory formulated by Hering in the late nineteenth century is the model on which the NCS System is based. Red-green, blue-yellow and black-white are called opponent pairs. This means that a colour can not be perceived as both reddish and greenish at the same time. Colours can however be perceived as reddish-yellow or reddish-blue. The transmission of colour signals to the brain is thought to be conducted according to the opponent colour theory.
NCS Primary Standard is a set of unique colour standards for the 1950 NCS colours and is used as reference for production of future standards.
NCS Quality Centre is at NCS Colour AB, Stockholm, Sweden (head office for NCS). The NCS Primary Standard is kept at the NCS Quality Centre. The SCI's certification to ISO 9002 is based on the checks that are carried out at the NCS Quality Centre.
NCS Quality Level Standard is the highest NCS quality level and is designed to be the standard for matching. All NCS Standard Sheets are individually measured. 100% have a deviation Delta E less than 0.5 from the NCS Primary Standard.
NCS Quality Level 1 is designed to be used for professional colour specifying material. Items are spot check controlled. 99% have a deviation Delta E less than 0.6 and 100% less than 1.0. Most of the NCS products are produced to Quality Level 1.
NCS Quality Level 2 is used for products that are produced in large quantities. Items are spot check controlled. 70% have a deviation Delta E less than 0.6, 90% less than 1.0 and 100% less than 1.5. The NCS Index and NCS Cascade fans are produced to Quality Level 2.
Redness is a colour's resemblance to the elementary colour red.
RGB is an abbreviation for Red, Green, Blue and is the colour breakdown used for displaying colour on screen.
|Saturation is the term used to describe the strength of a hue, or the purity of a colour. Colours with the same saturation are found along a straight line throught the black point (S) on the NCS Colour Triangle.|
Yellowness is a colour's resemblance to the elementary colour yellow.
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