Newton added a seventh colour, indigo, between blue and violet, but most people are not able to distinguish it and most color scientists do not recognize it as a separate colour it is sometimes designated as wavelengths of 420–440 nm. The colour table should not be interpreted as a definitive list – the pure spectral colors form a continuous spectrum, and how it is divided into distinct colors is a matter of culture, taste, and language. The wavelengths are measured in vacuum (see refraction). The colour table at right shows approximate frequencies (in terahertz) and wavelengths (in nanometers) for various pure spectral colors. The familiar colors of the rainbow in the spectrum – named from the Latin word for appearance or apparition by Isaac Newton in 1671 – contains all those colors that can be produced by visible light of a single wavelength only, the pure spectral or monochromatic colors. In each such class the members are called metamers of the colour in question. In fact, one may formally define a color as a class of spectra that give rise to the same colour sensation, although such classes would vary widely among different species, and to a lesser extent among individuals within the same species. Although the spectrum of light arriving at the eye from a given direction determines the color perceived in that direction, there are many more possible spectral combinations than color sensations. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 380 nm to 740 nm), it is known as "visible light."Ī given light source may emit light at many different wavelengths (and most do) its spectrum is then a distribution giving its intensity at each wavelength. Colour, wavelength, frequency and energy of light ColourĮlectromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. The narrow red, green and blue bars below the main bar show the relative intensities of the three primary colors mixed to make the colour directly above. Physics of colour The colors of the visible light spectrum colourĬomputer "spectrum". It includes the perception of color by the human eye and brain, the origin of colour in materials, colour theory in art, and the physics of electromagnetic radiation in the visible range (that is, what we commonly refer to simply as light). The science of colour is sometimes called chromatics. These physical or physiological quantifications of color, however, do not fully explain the psychophysical perception of colour appearance. Since perception of colour stems from the varying sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate these cells.
![physicus color mode physicus color mode](http://hyperphysics.phy-astr.gsu.edu/hbase/vision/imgvis/cie4.gif)
![physicus color mode physicus color mode](https://i.stack.imgur.com/xe9A1.jpg)
Typically, only features of the composition of light that are detectable by humans (wavelength spectrum from 400 nm to 700 nm, roughly) are included, thereby objectively relating the psychological phenomenon of color to its physical specification. Color categories and physical specifications of colour are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra. Colour derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Colour is an important part of the visual arts.Ĭolour (or colour, see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, yellow, white, etc.