Understanding Colors Theory The visible arts color concept


Colors Theory Within the visible arts color concept is a body of realistic steering to Colour mixing and the visible results of a special Colors mixture. There are additionally definitions (or classes) of colors established on the Colors wheel: major Colors secondary Colors and tertiary colour. Even though colour conception concepts first appeared in the writings of Leone Battista Alberti (c.1435) and the notebooks of Leonardo da Vinci (c.1490), a culture of “colory idea” began in the 18th century, initially inside a partisan controversy around Isaac Newton’s theory of Colors (Opticks, 1704) and the nature of most important colors. From there it developed as an unbiased creative subculture with most effective superficial reference to complimentary and imaginative and prescient science.Understanding Colors Theory

Understanding Colors Theory

Color derives from the spectrum of light (distribution of light power versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of color are also associated with objects or materials based on their physical properties such as light absorption, reflection, or emission spectra. By defining a color space, colors can be identified numerically by their coordinates.

Because 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. These physical or physiological quantification of color, however, do not fully explain the psychophysical perception of color appearance.

The science of color is sometimes called chromatics, colorimetry, or simply color science. 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 we commonly refer to simply as light).

electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. 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”.

Most light sources emit light at many different wavelengths; a source’s spectrum is a distribution giving its intensity at each wavelength. 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. 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. In each such class the members are called metamers of the color in question.

Understanding Colors Theory Spectral colors

Understanding Colors TheoryColors Theory 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. The table at right shows approximate frequencies (in terahertz) and wavelengths (in nano-meters) for various pure spectral colors. The wavelengths listed are as measured in air or vacuum (see refractive index).
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). A common list identifies six main bands: red, orange, yellow, green, blue, and violet. Newton’s conception included a seventh color, indigo, between blue and violet. It is possible that what Newton referred to as blue is nearer to what today we call cyan, and that indigo was simply the dark blue of the indigo dye that was being imported at the time.
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.
Understanding Colors Theory

The colors of the visible light spectrum

colorwavelength interval of colorfrequency interval
red~ 700–635 nm~ 430–480 THz
orange~ 635–590 nm~ 480–510 THz
yellow~ 590–560 nm~ 510–540 THz
green~ 560–520 nm~ 540–580 THz
cyan~ 520–490 nm~ 580–610 THz
blue~ 490–450 nm~ 610–670 THz
violet~ 450–400 nm~ 670–750 THz
Color of objects

Colors Theory The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain. Physically, objects can be said to have the color of the light leaving their surfaces, which normally depends on the spectrum of the incident illumination and the reflectance properties of the surface, as well as potentially on the angles of illumination and viewing. Some objects not only reflect light, but also transmit light or emit light themselves, which also contribute to the color. A viewer’s perception of the object’s color depends not only on the spectrum of the light leaving its surface, but also on a host of contextual cues, so that color differences between objects can be discerned mostly independent of the lighting spectrum, viewing angle, etc. This effect is known as color constancy.

Some generalizations of the physics can be drawn, neglecting perceptual effects for now:

Light arriving at an opaque surface is either reflected “specularly” (that is, in the manner of a mirror), scattered (that is, reflected with diffuse scattering), or absorbed – or some combination of these.

Opaque objects that do not reflect specularly (which tend to have rough surfaces) have their color determined by which wavelengths of light they scatter strongly (with the light that is not scattered being absorbed). If objects scatter all wavelengths with roughly equal strength, they appear white. If they absorb all wavelengths, they appear black.

Opaque objects that specularly reflect light of different wavelengths with different efficiencies look like mirrors tinted with colors determined by those differences. An object that reflects some fraction of impinging light and absorbs the rest may look black but also be faintly reflective; examples are black objects coated with layers of enamel or lacquer.

Objects that transmit light are either translucent (scattering the transmitted light) or transparent (not scattering the transmitted light). If they also absorb (or reflect) light of various wavelengths deferentially, they appear tinted with a color determined by the nature of that absorption.

Objects may emit light that they generate from having excited electrons, rather than merely reflecting or transmitting light. The electrons may be excited due to elevated temperature (incandescence), as a result of chemical reactions (chemo luminescence), after absorbing light of other frequencies (“fluorescence” or “phosphorescence”) or from electrical contacts as in light emitting diodes, or other light sources.