Colour basis

What is this? How it is produced?

 Colour basis-perceptionColour basis-wavelength-figure

Colour is a property of light that depends on wavelength. When light falls on an object, some of it is absorbed and some is reflected. The apparent colour of an opaque object depends on the wavelength of the light that it reflects; e.g., a red object observed in daylight appears red because it reflects only the waves producing red light. An opaque object that reflects all wavelengths appears white; one that absorbs all wavelengths appears black. Black and white are not generally considered true colours; black is said to result from the absence of colour, and white from the presence of all colours mixed together.Colour basis-colour absorbtion

Additive Colour Colours whose beams of light in various combinations can produce any of the colour sensations are called primary, or spectral, colours. The process of combining these colours is said to be additive: the sensations produced by different wavelengths of light are added together. The additive primaries of light are red, green, and blue-violet. White can be produced by combining all three primary colours. Any two colours whose light together produces white are called complementary colours, e.g., yellow and blue-violet, or red and blue-green.

Colour basis-additivecolor

Subtractive Colour When pigments or dyes are mixed, the resulting sensations differ from those of the transmitted primary colours. The process in this case is “subtractive,” since the pigments subtract or absorb some of the wavelengths of light. With transparent dyes, like our Fibre Reactive Dyes that we use for Tie-Dye, Cyan (blue-green), Magenta (red-violet), and Yellow and are called subtractive primaries, or primary colours. This is called the CMY system, and you use a CMY colour wheel. (With more opaque pigmented products, like our fabric paints, use traditional Red, Yellow and Blue as primaries and use a Red, Yellow, Blue colour wheel.) A mixture of cyan and yellow pigments yields green, the only colour not absorbed by one pigment or the other. A mixture of the three primary pigments produces black. These subtractive primary colours are the ones we use when dyeing, and the Fibre Reactive Dye equivalents are Turquoise, Fuchsia, and Lemon Yellow.

Colour basis-subtractive

Sources:

http://www.dharmatrading.com/home/color-and-dye-chemistry.html

Color and how to use it, 2010,By William F.Powel

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