# Color By [imsolo.eth](https://paragraph.com/@imsolo) · 2023-04-14 --- **Color** ([American English](https://en.wikipedia.org/wiki/American_English)) or **colour** ([Commonwealth English](https://en.wikipedia.org/wiki/Commonwealth_English)) is the [visual perception](https://en.wikipedia.org/wiki/Visual_perception) based on the [electromagnetic spectrum](https://en.wikipedia.org/wiki/Electromagnetic_spectrum). Though color is not an [inherent property](https://en.wikipedia.org/wiki/Inherence) of matter, color perception is related to an object's [light absorption](https://en.wikipedia.org/wiki/Absorption_\(electromagnetic_radiation\)), [reflection](https://en.wikipedia.org/wiki/Reflectance), [emission spectra](https://en.wikipedia.org/wiki/Emission_spectrum) and [interference](https://en.wikipedia.org/wiki/Wave_interference). For most humans, color are perceived in the visible [light](https://en.wikipedia.org/wiki/Light) spectrum with three types of [cone cells](https://en.wikipedia.org/wiki/Cone_cell) ([trichromacy](https://en.wikipedia.org/wiki/Trichromacy)). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelength, such as [bees](https://en.wikipedia.org/wiki/Bee) that can distinguish [ultraviolet](https://en.wikipedia.org/wiki/Ultraviolet), and thus has a different color sensitivity range. Animal perception of color originates from different light [wavelength](https://en.wikipedia.org/wiki/Wavelength) or [spectral sensitivity](https://en.wikipedia.org/wiki/Spectral_sensitivity) in cone cell types, which is then processed by the [brain](https://en.wikipedia.org/wiki/Brain). Colors have perceived properties such as [hue](https://en.wikipedia.org/wiki/Hue), [colorfulness](https://en.wikipedia.org/wiki/Colorfulness) (saturation) and [luminance](https://en.wikipedia.org/wiki/Luminance). Colors can also be [additively mixed](https://en.wikipedia.org/wiki/Additive_color) (commonly used for actual light) or [subtractively mixed](https://en.wikipedia.org/wiki/Subtractive_color) (commonly used for materials). If the colors are mixed in the right proportions, because of [metamerism](https://en.wikipedia.org/wiki/Metamerism_\(color\)), they may look the same as a single-wavelength light. For convenience, colors can be organized in a [color space](https://en.wikipedia.org/wiki/Color_space), which when being abstracted as a mathematical [color model](https://en.wikipedia.org/wiki/Color_model) can assign each region of color with a corresponding set of numbers. As such, color spaces are an essential tool for [color reproduction](https://en.wikipedia.org/wiki/Color_reproduction) in [print](https://en.wikipedia.org/wiki/Color_printing), [photography](https://en.wikipedia.org/wiki/Color_photography), computer monitors and [television](https://en.wikipedia.org/wiki/Color_television). The most well-known color models are [RGB](https://en.wikipedia.org/wiki/RGB_color_model), [CMYK](https://en.wikipedia.org/wiki/CMYK_color_model), [YUV](https://en.wikipedia.org/wiki/YUV), [HSL and HSV](https://en.wikipedia.org/wiki/HSL_and_HSV). Because the perception of color is an important aspect of human life, different colors have been associated with [emotions](https://en.wikipedia.org/wiki/Emotion), activity, and [nationality](https://en.wikipedia.org/wiki/Nationality). Names of [color regions](https://en.wikipedia.org/wiki/Color_term) in different cultures can have different, sometimes overlapping areas. In [visual arts](https://en.wikipedia.org/wiki/Visual_arts), [color theory](https://en.wikipedia.org/wiki/Color_theory) is used to govern the use of colors in an [aesthetically pleasing](https://en.wikipedia.org/wiki/Aesthetics) and [harmonious](https://en.wikipedia.org/wiki/Harmony_\(color\)) way. The theory of color includes the [color complements](https://en.wikipedia.org/wiki/Complementary_colors); [color balance](https://en.wikipedia.org/wiki/Color_balance); and classification of [primary colors](https://en.wikipedia.org/wiki/Primary_color) (traditionally [red](https://en.wikipedia.org/wiki/Red), [yellow](https://en.wikipedia.org/wiki/Yellow), [blue](https://en.wikipedia.org/wiki/Blue)), [secondary colors](https://en.wikipedia.org/wiki/Secondary_color) (traditionally [orange](https://en.wikipedia.org/wiki/Orange_\(colour\)), [green](https://en.wikipedia.org/wiki/Green), [purple](https://en.wikipedia.org/wiki/Purple)) and [tertiary colors](https://en.wikipedia.org/wiki/Tertiary_color). The study of colors in general is called [color science](https://en.wikipedia.org/wiki/Color_science). [Electromagnetic radiation](https://en.wikipedia.org/wiki/Electromagnetic_radiation) is characterized by its [wavelength](https://en.wikipedia.org/wiki/Wavelength) (or [frequency](https://en.wikipedia.org/wiki/Frequency)) and its [intensity](https://en.wikipedia.org/wiki/Luminous_intensity). When the wavelength is within the [visible spectrum](https://en.wikipedia.org/wiki/Visible_spectrum) (the range of wavelengths humans can perceive, approximately from 390 [nm](https://en.wikipedia.org/wiki/Nanometre) to 700 nm), it is known as "visible [light](https://en.wikipedia.org/wiki/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](https://en.wiktionary.org/wiki/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_](https://en.wikipedia.org/wiki/Metamerism_\(color\)) of the color in question. This effect can be visualized by comparing the light sources' [spectral power distributions](https://en.wikipedia.org/wiki/Spectral_power_distribution) and the resulting colors. ### Spectral colors _Main article:_ [_Spectral color_](https://en.wikipedia.org/wiki/Spectral_color) The familiar colors of the [rainbow](https://en.wikipedia.org/wiki/Rainbow) in the [spectrum](https://en.wikipedia.org/wiki/Visible_spectrum)—named using the [Latin](https://en.wikipedia.org/wiki/Latin) word for _appearance_ or _apparition_ by [Isaac Newton](https://en.wikipedia.org/wiki/Isaac_Newton) in 1671—include all those colors that can be produced by visible [light](https://en.wikipedia.org/wiki/Light) of a single wavelength only, the [_pure spectral_ or _monochromatic_ colors](https://en.wikipedia.org/wiki/Spectral_color). The table at right shows approximate frequencies (in [terahertz](https://en.wikipedia.org/wiki/Hertz)) and wavelengths (in [nanometers](https://en.wikipedia.org/wiki/Nanometre)) for spectral colors in the visible range. Spectral colors have 100% [purity](https://en.wikipedia.org/wiki/Colorfulness#Excitation_purity), and are fully [saturated](https://en.wikipedia.org/wiki/Colorfulness). A complex mixture of spectral colors can be used to describe any color, which is the definition of a light [power spectrum](https://en.wikipedia.org/wiki/Spectral_density#Power_spectral_density). The color table should not be interpreted as a definitive list; the spectral colors form a continuous spectrum, and how it is divided into [distinct colors linguistically](https://en.wikipedia.org/wiki/Color_term) is a matter of culture and historical contingency.[\[1\]](https://en.wikipedia.org/wiki/Color#cite_note-1) Despite the ubiquitous [ROYGBIV](https://en.wikipedia.org/wiki/ROYGBIV) mnemonic used to remember the spectral colors in English, the inclusion or exclusion of colors in this table is contentious, with disagreement often focused on [indigo](https://en.wikipedia.org/wiki/Indigo#Classification_as_a_spectral_color) and cyan.[\[2\]](https://en.wikipedia.org/wiki/Color#cite_note-2) Even if the subset of color terms is agreed, their wavelength ranges and borders between them may not be. The _intensity_ of a spectral color, relative to the context in which it is viewed, may alter its perception considerably according to the [Bezold–Brücke shift](https://en.wikipedia.org/wiki/Bezold%E2%80%93Br%C3%BCcke_shift); for example, a low-intensity orange-yellow is [brown](https://en.wikipedia.org/wiki/Brown), and a low-intensity yellow-green is [olive green](https://en.wikipedia.org/wiki/Olive_\(color\)#Olive_green). ### Color of objects The color of an object depends on how it [absorbs](https://en.wikipedia.org/wiki/Absorbance) and [scatters](https://en.wikipedia.org/wiki/Scattering) light. Most objects scatters light to some degree and do not reflect or transmit light [specularly](https://en.wikipedia.org/wiki/Specular_reflection) like [glasses](https://en.wikipedia.org/wiki/Glass) or [mirrors](https://en.wikipedia.org/wiki/Mirror). A [transparent](https://en.wikipedia.org/wiki/Transparency_\(optics\)) object allows almost all light to [transmit](https://en.wikipedia.org/wiki/Transmittance) or pass through, thus transparent objects are perceived as colorless. Conversely, an [opaque](https://en.wikipedia.org/wiki/Opacity_\(optics\)) object does not allow light to transmit through and instead absorbing or [reflecting](https://en.wikipedia.org/wiki/Reflection_\(physics\)) the light it receives. Like transparent objects, [translucent](https://en.wikipedia.org/wiki/Translucency) objects allow light to transmit through, but translucent objects are seen colored because they scatter or absorb certain wavelengths of light via internal scatterance. The absorbed light is often dissipated as [heat](https://en.wikipedia.org/wiki/Heat).[\[3\]](https://en.wikipedia.org/wiki/Color#cite_note-:0-3): 5–9, 12 [https://opensea.io/assets/0x72e19Be66354a8FB302Ca736F90c3bf9169B5c9c/0](https://opensea.io/assets/0x72e19Be66354a8FB302Ca736F90c3bf9169B5c9c/0) --- *Originally published on [imsolo.eth](https://paragraph.com/@imsolo/color)*