Achromatic colours

Achromatic colours resemble only black and white (grey). 

Chroma is the attribute of a colour that expresses the degree by which it differs from an achromatic colour of the same lighmess. 

Information on the hue of whiteness is provided by dividing CIE colour space, in the neighbourhood of the D65 achromatic point, into a series of parallel strips corresponding to variations in hue of whiteness. The principle is illustrated in Figure 11.4. According to this... 

There is a highly complex series of connections between the detector and fibres making up the optic nerve taking the resulting signals to the visual cortex. This link can be depicted using a simplified hypothetical framework (Hunt 1998). There appear to be not four but three types of nerve fibre. One carries achromatic or brightness information, the other two carry colour information -the opponent colour mechanisms. This model is shown in Fig. 2.2. 

A coloured backgrormd caused by optical interference is the most serious disadvantage of the STN-LCD because it degrades the colour reproduction of an LCD display. To solve this problem and produce an achromatic black-and-white bacl rormd, the double-layered STN-LCD (D-STN-LCD), which comprises a liquid crystal optical compensator mounted on the STN-LCD, has been developed [4]. Figure 4.3.5 shows the principle of the D-STN-LCD. The compensation layer, which is placed ready fabricated on the driven cell, compensates the optical dispersion caused by the birefringence effect and decolourizes the STN-LCD as long as the following three conditions are met ... 

The daylight reflectance of a specimen expressed on a scale extending from 0 for ideal black to 10 for ideal white by steps of approximately equal visual importance. Achromatic or neutral colors are designated N followed by the value notation, thus N 5.0. (Colour physics for industry, 2nd edn. McDonald, Roderick (eds) Society of Dyers and Colourists, West Yorkshire, England, 1997)... 

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