Colour Order Systems
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H30: Specification of Colour, Munsell and NCS> The most useful methods of specifying the colour appearance of an object or a surface are those that do not lead to confusion and where the method has a clear interpretation. In this section we will be looking at the way that colours can be specified by selecting samples from a colour atlas which forms part of a colour order system. The Munsell and the NCS colour order systems are described.
Colour Numbers RGB
ver>H31-V02 [Home]
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H31: Putting Numbers to Colour: CIE RGB> Numerical methods of describing colour communicate colour information without the need for physical samples. Ideally the numbers should by easily interpreted in terms of attributes such as lightness, chroma or hue. The RGB system adopted by the CIE (Commission Internationale de l'╔clairage) in the 1930's is based on the principles of additive mixing of coloured lights and the trichromatic theory of colour vision.
Colour Numbers XYZ
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H32: Putting Numbers to Colour: CIE X Y Z> In 1931, the 8th session of the Commission Internationale de l' Eclairage (CIE) held in Cambridge, England, devised a system that provided numerical specificatio for all visible colours. This was based on defining a new set of additive primaries X, Y, and Z based on the R G B set defined in the CIE RGB system.
Colour Numbers Lab
ver>H33-V02 [Home]
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H33: Putting Numbers to Colour: CIE L*a*b*> For practical day to day application the CIE L* a* b* system has become the accepted method of representing the appearance of surface colours . CIE L*a*b* colour space was introduced in 1976 and the structure is based on the opponent theory of colour vision.
Colour Numbers sRGB
ver>H34-V02 [Home]
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H34: Putting Numbers to Colour: sRGB>In the community of devices and industries that communicate colour information with R G B, there are many confusing and often incompatible R G B practices and standards. Exactly which colour is represented by the R G B data stored in an image file is not well defined. The objective of sRGB is to provide a workable solution that solves most of the colour communication problems for office, home and web users.
Colour Difference Vis.
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H35: Visual Assessment of Colour Difference> The link between colour impression and product quality is very strong especially in a prestige product. It can be expensive to correct the colour of an off-shade finished product, not just in terms of wasted materials but also in terms of the time involved. The most reliable visual judgement of the colour of a material is made by a direct, side-by-side comparison of the colour of the test panel with the colour of the sample panel.
Colour Difference Inst.
ver>H36-V02 [Home]
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H36: Instrument Assessment of Colour Difference> Instrument based methods of judging the colour appearance measure the colour co-ordinates of the test and of the standard panel and then determine the total colour difference dE*, and the component differences dL* (lightness) dC* (intensity of colour) and dH* (hue).
Colour Measurement
ver>H37-V02 [Home]
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H37: Measurement of Colour> Instrument based methods is becoming normal practice for the assessment of the colour and colour difference of flat, uniform surfaces. The use of microprocessor chips and the developments in optics has meant that the size, ease of use and the performance of the instruments have improved dramatically and the cost has been reduced.
 
 
 
 
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