Editing Color (section)

== Reproduction ==

{{main|Color reproduction}}

[[File:CIE chromaticity diagram 2012 version.png|thumb|upright=1.25|The [[CIE 1931 color space]] xy [[chromaticity]] diagram with the visual locus plotted using the CIE (2006) physiologically relevant LMS fundamental color matching functions transformed into the CIE 1931 xy [[color space]] and converted into [[Adobe RGB]]; the triangle shows the [[gamut]] of Adobe RGB, the [[Planckian locus]] is shown with color temperatures labeled in [[Kelvin]]s, the outer curved boundary is the spectral (or monochromatic) locus, with wavelengths shown in nanometers, the colors in this file are being specified using Adobe RGB, areas outside the triangle cannot be accurately rendered since they are outside the gamut of Adobe RGB, therefore they have been interpreted, the colors depicted depend on the gamut and color accuracy of your display]]

Color reproduction is the science of creating colors for the human eye that faithfully represent the desired color. It focuses on how to construct a spectrum of wavelengths that will best evoke a certain color in an observer. Most colors are not [[#Spectral colors|spectral color]]s, meaning they are mixtures of various wavelengths of light. However, these non-spectral colors are often described by their [[dominant wavelength]], which identifies the single wavelength of light that produces a sensation most similar to the non-spectral color. Dominant wavelength is roughly akin to [[hue]].

There are many color perceptions that by definition cannot be pure spectral colors due to [[colorfulness|desaturation]] or because they are [[purple]]s (mixtures of red and violet light, from opposite ends of the spectrum). Some examples of necessarily non-spectral colors are the achromatic colors ([[black]], [[gray]], and [[white]]) and colors such as [[pink]], [[tan (color)|tan]], and [[magenta]].

Two different light spectra that have the same effect on the three color receptors in the human eye will be perceived as the same color. They are [[metamerism (color)|metamer]]s of that color. This is exemplified by the white light emitted by fluorescent lamps, which typically has a spectrum of a few narrow bands, while daylight has a continuous spectrum. The human eye cannot tell the difference between such light spectra just by looking into the light source, although the [[color rendering index]] of each light source may affect the color of objects illuminated by these metameric light sources.

Similarly, most human color perceptions can be generated by a mixture of three colors called ''primaries''. This is used to reproduce color scenes in photography, printing, television, and other media. There are a number of methods or [[color space]]s for specifying a color in terms of three particular [[primary color]]s. Each method has its advantages and disadvantages depending on the particular application.

No mixture of colors, however, can produce a response truly identical to that of a spectral color, although one can get close, especially for the longer wavelengths, where the [[CIE 1931 color space]] chromaticity diagram has a nearly straight edge. For example, mixing green light (530&nbsp;nm) and blue light (460&nbsp;nm) produces cyan light that is slightly desaturated, because response of the red color receptor would be greater to the green and blue light in the mixture than it would be to a pure cyan light at 485&nbsp;nm that has the same intensity as the mixture of blue and green.

Because of this, and because the ''primaries'' in [[color printing]] systems generally are not pure themselves, the colors reproduced are never perfectly saturated spectral colors, and so spectral colors cannot be matched exactly. However, natural scenes rarely contain fully saturated colors, thus such scenes can usually be approximated well by these systems. The range of colors that can be reproduced with a given color reproduction system is called the [[gamut]]. The [[International Commission on Illumination|CIE]] chromaticity diagram can be used to describe the gamut.

Another problem with color reproduction systems is connected with the initial measurement of color, or [[colorimetry]]. The characteristics of the color sensors in measurement devices (e.g. cameras, scanners) are often very far from the characteristics of the receptors in the human eye.

A color reproduction system "tuned" to a human with normal color vision may give very inaccurate results for other observers, according to color vision deviations to the standard observer.

The different color response of different devices can be problematic if not properly managed. For color information stored and transferred in digital form, [[color management]] techniques, such as those based on [[ICC profile]]s, can help to avoid distortions of the reproduced colors. Color management does not circumvent the gamut limitations of particular output devices, but can assist in finding good mapping of input colors into the gamut that can be reproduced.

=== Additive coloring<span class="anchor" id="Additive colouring"></span> ===
[[File:AdditiveColor.svg|thumb|Additive color mixing: combining red and green yields yellow; combining all three primary colors together yields white]]
[[Additive color]] is light created by mixing together [[light]] of two or more different colors.<ref>{{cite web |last1=MacEvoy |first1=Bruce |title=handprint : colormaking attributes |url=https://www.handprint.com/HP/WCL/color5.html#theoryadd |access-date=26 February 2019 |website=www.handprint.com}}</ref><ref name="briggs">{{cite web |author=David Briggs |year=2007 |title=The Dimensions of Color |url=http://www.huevaluechroma.com/044.php |url-status=live |archive-url=https://web.archive.org/web/20150928031404/http://www.huevaluechroma.com/044.php |archive-date=2015-09-28 |access-date=2011-11-23}}</ref> [[Red]], [[green]], and [[blue]] are the additive [[primary color]]s normally used in additive color systems such as projectors, televisions, and computer terminals.

=== Subtractive coloring<span class="anchor" id="Subtractive colouring"></span> ===
[[File:SubtractiveColor.svg|thumb|Subtractive color mixing: combining yellow and magenta yields red; combining all three primary colors together yields black]]

[[Subtractive color]]ing uses dyes, inks, pigments, or filters to absorb some wavelengths of light and not others.<ref>{{Cite web |title=Molecular Expressions Microscopy Primer: Physics of Light and Color – Introduction to the Primary Colors |url=https://micro.magnet.fsu.edu/primer/lightandcolor/primarycolorsintro.html |access-date=2023-12-08 |website=micro.magnet.fsu.edu}}</ref> The color that a surface displays comes from the parts of the visible spectrum that are not absorbed and therefore remain visible. Without pigments or dye, fabric fibers, paint base and paper are usually made of particles that scatter white light (all colors) well in all directions. When a pigment or ink is added, wavelengths are absorbed or "subtracted" from white light, so light of another color reaches the eye.

If the light is not a pure white source (the case of nearly all forms of artificial lighting), the resulting spectrum will appear a slightly different color. [[Red]] paint, viewed under [[blue]] light, may appear [[black]]. Red paint is red because it scatters only the red components of the spectrum. If red paint is illuminated by blue light, it will be absorbed by the red paint, creating the appearance of a black object.

The subtractive model also predicts the color resulting from a mixture of paints, or similar medium such as fabric dye, whether applied in layers or mixed together prior to application. In the case of paint mixed before application, incident light interacts with many different pigment particles at various depths inside the paint layer before emerging.<ref>{{cite book |last1=Williamson |first1=Samuel J |title=Light and Color in Nature and Art |last2=Cummins |first2=Herman Z |date=1983 |publisher=John Wiley & Sons, Inc. |isbn=0-471-08374-7 |location=New York |pages=28–30 |quote="Thus subtractive color mixing laws that successfully describe how light is altered by nonspectral filters also describes how light is altered by pigments."}}</ref>

=== Structural color<span class="anchor" id="Structural colour"></span> ===
{{further|Structural coloration|Animal coloration}}
[[File:Peacock feathers closeup.jpg|thumb|The bright colors of Peacock feathers are caused by structural coloration]]
Structural colors are colors caused by interference effects rather than by pigments. Color effects are produced when a material is scored with fine parallel lines, formed of one or more parallel thin layers, or otherwise composed of microstructures on the scale of the color's [[wavelength]]. If the microstructures are spaced randomly, light of shorter wavelengths will be scattered preferentially to produce [[Tyndall effect]] colors: the blue of the sky (Rayleigh scattering, caused by structures much smaller than the wavelength of light, in this case, air molecules), the luster of [[opal]]s, and the blue of human irises. If the microstructures are aligned in arrays, for example, the array of pits in a CD, they behave as a [[diffraction grating]]: the grating reflects different wavelengths in different directions due to [[wave interference|interference]] phenomena, separating mixed "white" light into light of different wavelengths. If the structure is one or more thin layers then it will reflect some wavelengths and transmit others, depending on the layers' thickness.

Structural color is studied in the field of [[thin-film optics]]. The most ordered or the most changeable structural colors are [[iridescent]]. Structural color is responsible for the blues and greens of the feathers of many birds (the blue jay, for example), as well as certain butterfly wings and beetle shells. Variations in the pattern's spacing often give rise to an iridescent effect, as seen in [[peacock]] feathers, [[soap bubble]]s, films of oil, and [[mother of pearl]], because the reflected color depends upon the viewing angle. Numerous scientists have carried out research in butterfly wings and beetle shells, including Isaac Newton and Robert Hooke. Since 1942, [[electron microscope|electron micrography]] has been used, advancing the development of products that exploit structural color, such as "[[photonic]]" cosmetics.<ref>{{cite web|url=http://www.esrc.ac.uk/ESRCInfoCentre/about/CI/events/FSS/2006/science.aspx?ComponentId=14867&SourcePageId=14865|title=Economic and Social Research Council: Science in the Dock, Art in the Stocks|access-date=2007-10-07|url-status=dead|archive-url=https://web.archive.org/web/20071102025015/http://www.esrc.ac.uk/ESRCInfoCentre/about/CI/events/FSS/2006/science.aspx?ComponentId=14867&SourcePageId=14865|archive-date=November 2, 2007}}</ref>