White

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This article is about the color. For other uses, see White (disambiguation).

"White light" redirects here. For other uses, see White Light.

White
— Commonly represents —
Purity, lack, snow, ice, peace, life, death, nothing, frost, good, air
— Color coordinates —
Hex triplet		#FFFFFF
RGBB	(r, g, b)	(255, 255, 255)
HSV	(h, s, v)	(-°, 0%, 100%)
Source		By definition
B: Normalized to [0–255] (byte)

White is a color, the perception which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in near equal amount and with high brightness compared to the surroundings.

Since the impression of white is obtained by three summations of light intensity across the visible spectrum, the number of combinations of light wavelengths that produce the sensation of white is practically infinite. There are a number of different white light sources such as the midday Sun, incandescent lamps, fluorescent lamps and white LEDs. The impression of white light can also be created by mixing appropriate intensities of the primary colors of light — red, green and blue (RGB) — a process called additive mixing, as seen in many display technologies.

White light reflected off objects can be seen when no part of the light spectrum is reflected significantly more than others and the reflecting material has a degree of diffusion. This is seen when transparent fibers, particles, or droplets are in a transparent matrix of a substantially different refractive index. Examples include classic "white" substances such as sugar, foam, pure sand or snow, cotton, clouds, and milk. Crystal boundaries and imperfections can also make otherwise transparent materials white, as in the milky quartz or the microcrystalline structure of a seashell. This is also true for artificial paints and pigments, where white results when finely divided transparent material of a high refractive index is suspended in a contrasting binder. Typically paints contain calcium carbonate and/or synthetic rutile with no other pigments if a white color is desired.

Shade

[edit] Light

White light refracted in a prism revealing the color components.

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 this was not true by passing white light through a prism, then through another prism. If the colors were added by the prism, the second prism should have added further colors to the single-colored beam. Since the single-colored beam remained a single color, Newton concluded that the prism merely separated the colors already present in the light. White light is the effect of combining the visible colors of light in equal proportions.

In the science of lighting, there is a continuum of colors of light that can be called "white". One set of colors that deserves this description is the color emitted via the process called incandescence, by a black body at various relatively-high temperatures. For example, the color 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 color temperature of about 3200 K. Daylight 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.

[edit] Paint

In painting, white can be crafted by reflecting ambient light from a white pigment, although the ambient light must be white light, or else the white pigment will appear the color of the light. White when mixed with black produces gray.^{[citation needed]} To art students, the use of white can present particular problems, and there is at least one training course specializing in the use of white in art.^{[citation needed]} In watercolor painting, white areas are the absence of paint on the paper. When mixing paints in order to get a lighter color, it's advisable to mix a small amount of color to white, rather than trying to add white to the color, as it will take considerably more paint to get the desired tint.

[edit] Objects

While the color of a light source can be reasonably measured by its correlated color temperature, a different approach is required for objects since different samples may appear white without a reference. Thus, assessment of whiteness requires a comparison. The International Commission on Illumination (CIE) prescribes one such method.

[edit] Computer color temperature

Computer displays often have a color temperature control, allowing the user to select the color temperature (usually from a small set of fixed values) of the light emitted when the computer produces the electrical signal corresponding to "white". The RGB coordinates of white are (255, 255, 255).