Some objects not only reflect light, but also transmit light or emit light themselves, which also contributes to the color. The perceived color normally depends on the spectrum of the incident illumination, the wave velocity, the reflectance properties of the surface, and potentially on the angles of illumination and viewing. Physically, objects can be said to have the color of the light leaving their surfaces if it travels through the vacuum of space at speed c and does not pass through a physical medium such as a prism. The color of an object depends on the physics of the object in its environment, the physics of light in its environment, and the characteristics of the perceiving eye and brain. The intensity of a spectral color, relative to the context in which it is viewed, may alter its perception considerably for example, a low-intensity orange-yellow is brown, and a low-intensity yellow-green is olive green. It is possible that what Newton referred to as blue is nearer to what today is known as cyan, and that indigo was simply the dark blue of the indigo dye that was being imported at the time. Newton's conception included a seventh color, indigo, between blue and violet. A common list identifies six main bands: red, orange, yellow, green, blue, and violet. The color 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 linguistically is a matter of culture and historical contingency (although people everywhere have been shown to perceive colors in the same way ).
The wavelengths listed are as measured in air or vacuum (see refractive index). The table at right shows approximate frequencies (in tera hertz) and wavelengths (in nanometers) for various pure spectral colors. The familiar colors of the rainbow in the spectrum-named using the Latin word for appearance or apparition by Isaac Newton in 1671-include all those colors that can be produced by visible light of a single wavelength only, the pure spectral or monochromatic colors. This effect can be visualized by comparing the light sources' spectral power distributions and the resulting colors. In each such class the members are called metamers of the color in question. In fact, one may formally define a color as a class of spectra that give rise to the same color 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 sensation in that direction, there are many more possible spectral combinations than color sensations. Most light sources emit light at many different wavelengths a source's spectrum is a distribution giving its intensity at each wavelength. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as "visible light". The colors of the visible light spectrum ColorĬolor, wavelength, frequency and energy of lightĮlectromagnetic radiation is characterized by its wavelength (or frequency) and its intensity.
It includes the perception of color by the human eye and brain, the origin of color in materials, color theory in art, and the physics of electromagnetic radiation in the visible range (that is, what is commonly referred to simply as light).Ĭontinuous optical spectrum rendered into the sRGB color space. The science of color is sometimes called chromatics, colorimetry, or simply color science.
These physical or physiological quantifications of color, however, do not fully explain the psychophysical perception of color appearance. By defining a color space, colors can be identified numerically by their coordinates.īecause perception of color stems from the varying spectral 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. Color categories and physical specifications of color are associated with objects or materials based on their physical properties such as light absorption, reflection, or emission spectra. Color ( American English) or colour ( British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes.
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