|Table of contents|
2 White Light
3 Standard Whites
5 Usage, symbolism, colloquial expressions
6 People Whose Surname Is White
Until Newton's work became accepted, most scientists believed that white was the fundamental color of light; and that other colors were formed only by adding something to light. Newton demonstrated that White was formed by combining the other colors.
In the science of lighting, there is a continuum of colours of light that can be called "white". One set of colours that deserve this description are the colours emitted, via the process called incandescence, by a black body at various relatively-high temperatures. For example, the colour of a black body at a temperature of 2848 kelvins matches that produced by domestic incandescent light bulbs. It is said that "the color temperature of such a light bulb is 2848 K". The white light used in theatre illumination has a colour temperature of about 3200 K. Daylight has a nominal colour temperature of 5400 K (called equal energy white), but can vary from a cool red up to a bluish 25,000 K. Not all black body radiation can be considered white light: the background radiation of the universe, to name an extreme example, is only a few kelvins and is quite invisible.
Standard whites are often defined with reference to the International Commission on Illumination's (CIE's) chromaticity diagram. These are the D series of standard illuminants. Illuminant D65, originally corresponding to a colour temperature of 6,500 K, is taken to represent standard daylight.
Computer displays often have a colour temperature control, allowing the user to select the colour temperature (usually from a small set of fixed values) of the light emitted when the computer produces the electrical signal corresponding to "white".
Usage, symbolism, colloquial expressions