Hue
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For the city in Vietnam, see Hue (city).

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A hue refers to the gradation of color within the optical spectrum, or visible spectrum, of light. "Hue "may also refer to a particular color within this spectrum, as defined by its dominant wavelength. A color is defined by the central tendency of the light wave's wavelength. For example, a light wave with a central tendency within 565-590 nm will be yellow.

In painting color theory, a hue refers to a pure color —one without added white (tint) or black (shade) pigment.

In an RGB color space, hue can be thought of as an angle of rotation φ, such that φ=0° corresponds to red, φ=120° corresponds to green, and φ=240° corresponds to blue. Letting R, G, B be the color coordinates in RGB space, then after obtaining the brightness μ and the saturation σ, the hue could be obtained from

.

Compare with standard score. The RGB coordinates should be derivable from the μ, σ, φ coordinates as follows:

Hue is a coordinate (an angle of rotation) in HSB color space.

See also:

• HSV color space
• Brightness

The original article can be found at: http://en.wikipedia.org/wiki/Hue.
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