Editing Color temperature (section)

==Applications==
[[File:Kelvin Temperature Chart Vertical tightened.svg|thumb|397x397px|Color temperature (right) of various light sources (left)]]

===Lighting===
[[File:Incand-3500-5500-color-temp-comparison.png|thumb|alt=Color temperature comparison of common electric lamps|Color temperatures of common electric lamps|140x140px]]

For lighting building interiors, it is often important to take into account the color temperature of illumination. A warmer (i.e., a lower color temperature) light is often used in public areas to promote relaxation, while a cooler (higher color temperature) light is used to enhance concentration, for example in schools and offices.<ref>{{cite book
 | title = Encyclopedia of Laser Physics and Technology
 | author = Rüdiger Paschotta
 | publisher = Wiley-VCH
 | year = 2008
 | isbn = 978-3-527-40828-3
 | page = 219
 | url = https://books.google.com/books?id=BN026ye2fJAC&q=lighting%20color-temperature%20relaxing&pg=PA219
 }}{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

CCT dimming for LED technology is regarded as a difficult task, since binning, age and temperature drift effects of LEDs change the actual color value output. Here feedback loop systems are used, for example with color sensors, to actively monitor and control the color output of multiple color mixing LEDs.<ref>{{cite journal
 | title = Sensors and Feedback Control of Multi-Color LED Systems
 | author = Thomas Nimz, Fredrik Hailer and Kevin Jensen
 | journal = LED Professional Review: Trends & Technologie for Future Lighting Solutions
 | publisher = LED Professional
 | year = 2012
 | issn = 1993-890X
 | pages = 2–5
 | url = http://www.mazet.de/en/english-documents/english/featured-articles/sensors-and-feedback-control-of-multi-color-led-systems-1/download#.UX7VXYIcUZI
 | url-status = dead
 | archive-url = https://web.archive.org/web/20140429162806/http://www.mazet.de/en/english-documents/english/featured-articles/sensors-and-feedback-control-of-multi-color-led-systems-1/download#.UX7VXYIcUZI
 | archive-date = 2014-04-29
 }}</ref>

===Aquaculture===

In [[fishkeeping]], color temperature has different functions and foci in the various branches.

* In freshwater aquaria, color temperature is generally of concern only for producing a more attractive display.{{citation needed|date=August 2012}} Lights tend to be designed to produce an attractive spectrum, sometimes with secondary attention paid to keeping the plants in the aquaria alive.
* In a saltwater/reef [[aquarium]], color temperature is an essential part of tank health.  Within about 400 to 3000 nanometers, light of shorter wavelength can [[Electromagnetic absorption by water#Visible light absorption in liquid water|penetrate deeper into water]] than longer wavelengths,<ref>{{cite web|url=http://www.lsbu.ac.uk/water/vibrat.html|title=Water Absorption Spectrum|last=Chaplin|first=Martin|access-date=2012-08-01|url-status=live|archive-url=https://web.archive.org/web/20120717061228/http://www.lsbu.ac.uk/water/vibrat.html|archive-date=2012-07-17}}</ref><ref>{{cite journal |author=Pope R. M., Fry E. S. |year=1997 |title=Absorption spectrum (380–700 nm) of pure water. II. Integrating cavity measurements |journal=Applied Optics |volume=36 |issue=33 |pages=8710–8723 |publisher=Optical Society of America |doi=10.1364/AO.36.008710 |bibcode=1997ApOpt..36.8710P |pmid=18264420 |s2cid=11061625 }}</ref><ref>{{cite book |author=Jerlov N. G. |title=Marine Optics. |series=Elsevie Oceanography Series. |volume=14 |pages=128–129 |year=1976 |publisher=Elsevier Scientific Publishing Company |isbn=0-444-41490-8 |location=Amsterdam |url=https://books.google.com/books?id=tzwgrtnW_lYC&pg=PA128 |access-date=August 1, 2012 |url-status=live |archive-url=https://web.archive.org/web/20171221064443/https://books.google.com/books?id=tzwgrtnW_lYC&lpg=PA128&pg=PA128 |archive-date=December 21, 2017 }}</ref> providing essential energy sources to the algae hosted in (and sustaining) coral. This is equivalent to an increase of color temperature with water depth in this spectral range. Because coral typically live in shallow water and receive intense, direct tropical sunlight, the focus was once on simulating this situation with 6500&nbsp;K lights.

===Digital photography===
In [[digital photography]], the term color temperature sometimes refers to remapping of color values to simulate variations in ambient color temperature. Most digital cameras and raw image software provide presets simulating specific ambient values (e.g., sunny, cloudy, tungsten, etc.) while others allow explicit entry of white balance values in kelvins. These settings vary color values along the blue–yellow axis, while some software includes additional controls (sometimes labeled "tint") adding the magenta–green axis, and are to some extent arbitrary and a matter of artistic interpretation.<ref>{{cite web |url=http://www.chriskern.net/essay/realityCheck.html |title=Reality Check: Ambiguity and Ambivalence in Digital Color Photography |last=Kern |first=Chris |access-date=2011-03-11 |url-status=live |archive-url=https://web.archive.org/web/20110722001411/http://www.chriskern.net/essay/realityCheck.html |archive-date=2011-07-22 }}</ref>

===Photographic film===
{{unreferenced section|date=June 2012}}
Photographic emulsion film does not respond to lighting color identically to the human retina or visual perception. An object that appears to the observer to be white may turn out to be very blue or orange in a photograph. The [[color balance]] may need to be corrected during printing to achieve a neutral color print.  The extent of this correction is limited since color film normally has three layers sensitive to different colors and when used under the "wrong" light source, every layer may not respond proportionally, giving odd color casts in the shadows, although the mid-tones may have been correctly white-balanced under the enlarger.  Light sources with discontinuous spectra, such as fluorescent tubes, cannot be fully corrected in printing either, since one of the layers may barely have recorded an image at all.

Photographic film is made for specific light sources (most commonly daylight film and [[tungsten film]]), and, used properly, will create a neutral color print. Matching the [[sensitometry|sensitivity of the film]] to the color temperature of the light source is one way to balance color. If tungsten film is used indoors with incandescent lamps, the yellowish-orange light of the [[tungsten]] incandescent lamps will appear as white (3200&nbsp;K) in the photograph.  Color negative film is almost always daylight-balanced, since it is assumed that color can be adjusted in printing (with limitations, see above).  Color transparency film, being the final artefact in the process, has to be matched to the light source or filters must be used to correct color.

[[filter (photography)|Filters]] on a camera lens, or [[color gel]]s over the light source(s) may be used to correct color balance. When shooting with a bluish light (high color temperature) source such as on an overcast day, in the shade, in window light, or if using tungsten film with white or blue light, a yellowish-orange filter will correct this. For shooting with daylight film (calibrated to 5600&nbsp;K) under warmer (low color temperature) light sources such as sunsets, candlelight or [[tungsten lighting]], a bluish (e.g. #80A) filter may be used. More-subtle filters are needed to correct for the difference between, say 3200&nbsp;K and 3400&nbsp;K tungsten lamps or to correct for the slightly blue cast of some flash tubes, which may be 6000&nbsp;K.<ref name=":0">{{Cite book|last=Präkel|first=David|url=https://books.google.com/books?id=VHBUDwAAQBAJ&q=photography+lighting+kelvin&pg=PP1|title=Basics Photography 02: Lighting|date=2013-02-28|publisher=Bloomsbury Publishing|isbn=978-2-940447-55-8|language=en}}</ref>

If there is more than one light source with varied color temperatures, one way to balance the color is to use daylight film and place color-correcting gel filters over each light source.

Photographers sometimes use color temperature meters. These are usually designed to read only two regions along the visible spectrum (red and blue); more expensive ones read three regions (red, green, and blue). However, they are ineffective with sources such as fluorescent or discharge lamps, whose light varies in color and may be harder to correct for. Because this light is often greenish, a magenta filter may correct it. More sophisticated [[colorimetry]] tools can be used if such meters are lacking.<ref name=":0" />

===Desktop publishing===
{{unreferenced section|date=June 2012}}
In the desktop publishing industry, it is important to know a monitor's color temperature. Color matching software, such as Apple's [[List of macOS components#ColorSync Utility|ColorSync Utility]] for MacOS, measures a monitor's color temperature and then adjusts its settings accordingly. This enables on-screen color to more closely match printed color. Common monitor color temperatures, along with matching [[standard illuminant]]s in parentheses, are as follows:

*5000&nbsp;K (CIE D50)
*5500&nbsp;K (CIE D55)
*6500&nbsp;K ([[CIE Standard Illuminant D65|D65]])
*7500&nbsp;K (CIE D75)
*9300&nbsp;K

D50 is scientific shorthand for a [[standard illuminant]]: the daylight spectrum at a correlated color temperature of 5000&nbsp;K. Similar definitions exist for D55, D65 and D75. Designations such as ''D50'' are used to help classify color temperatures of [[light table]]s and viewing booths. When viewing a [[Reversal film|color slide]] at a light table, it is important that the light be balanced properly so that the colors are not shifted towards the red or blue.

[[Digital camera]]s, web graphics, [[DVD]]s, etc., are normally designed for a 6500&nbsp;K color temperature. The [[sRGB standard]] commonly used for images on the Internet stipulates a 6500&nbsp;K display [[white point]].

[[Microsoft Windows]] prior to [[Windows 10]] are use [[sRGB]] as default display color space, and use 6500 K as default display color temperature. [[Windows 10 1607]] have supports for [[high dynamic range]].<ref>{{Cite web |last=windows-driver-content |title=HEVC 10-Bit HDR Streaming Playback Test 1 |url=https://learn.microsoft.com/en-us/windows-hardware/test/hlk/testref/7ecb10c2-5c2d-4f67-a29c-6ffeb9da2812 |access-date=2025-05-14 |website=learn.microsoft.com |language=en-us}}</ref> [[Windows 11 22H2]] have supports for Auto Color Management (ACM) which further optimized for [[OLED]] monitors by reading [[EDID]] data.<ref> {{Cite web |title=Auto color management in Windows 11 - Microsoft Support |url=https://support.microsoft.com/en-us/windows/auto-color-management-in-windows-11-64a4de7f-9c93-43ec-bdf1-3b12ffa0870b |access-date=2024-09-04 |website=support.microsoft.com}}</ref>

Apple [[iOS]], [[iPadOS]] and [[macOS]] are use [[sRGB]] and [[DCI-P3]] as default display color spaces.<ref> {{Cite web |title=Use reference modes with your Apple display |url=https://support.apple.com/en-us/108321 |access-date=2025-03-30 |website=Apple Support |language=en}}</ref>

===TV, video, and digital still cameras===
{{unreferenced section|date=June 2012}}
The [[NTSC]] and [[PAL]] TV norms call for a compliant TV screen to display an electrically black and white signal (minimal color saturation) at a color temperature of 6500&nbsp;K. On many consumer-grade televisions, there is a very noticeable deviation from this requirement. However, higher-end consumer-grade televisions can have their color temperatures adjusted to 6500&nbsp;K by using a preprogrammed setting or a custom calibration. Current versions of [[ATSC (standards)|ATSC]] explicitly call for the color temperature data to be included in the data stream, but old versions of ATSC allowed this data to be omitted. In this case, current versions of ATSC cite default colorimetry standards depending on the format. Both of the cited standards specify a 6500&nbsp;K color temperature.

Most video and digital still cameras can adjust for color temperature by zooming into a white or neutral colored object and setting the manual "white balance" (telling the camera that "this object is white"); the camera then shows true white as white and adjusts all the other colors accordingly. White-balancing is necessary especially when indoors under fluorescent lighting and when moving the camera from one lighting situation to another. Most cameras also have an automatic white balance function that attempts to determine the color of the light and correct accordingly. While these settings were once unreliable, they are much improved in today's digital cameras and produce an accurate white balance in a wide variety of lighting situations.

However, in [[NTSC-J]] and [[NTSC-C]] standards, 9300 K color temperature is recommended. TVs and projectors sold in Japan, South Korea, China, Hong Kong, Taiwan and Philippines are usually adopt 9300 K as default settings. But for compatibility reasons, [[computer monitor]]s sold in these country/region are usually adopt 6500 K as default settings; these color temperature settings are usually tuneable in [[on-screen display|OSD]] menu.

===Artistic application via control of color temperature===
{{unreferenced section|date=June 2012}}
[[File:Example different color temp.jpg|right|thumb|180px|The house above appears a light cream during midday, but seems to be bluish white here in the dim light before full sunrise. Note the color temperature of the sunrise in the background.]]

Video [[camera operator]]s can white-balance objects that are not white, downplaying the color of the object used for white-balancing. For instance, they can bring more warmth into a picture by white-balancing off something that is light blue, such as faded blue denim; in this way white-balancing can replace a filter or lighting gel when those are not available.

[[Cinematographer]]s do not "white balance" in the same way as video camera operators; they use techniques such as filters, choice of film stock, [[pre-flashing]], and, after shooting, [[color grading]], both by exposure at the labs and also digitally. Cinematographers also work closely with set designers and lighting crews to achieve the desired color effects.<ref>{{Cite book|last=Brown|first=Blain|url=https://books.google.com/books?id=GiQlDwAAQBAJ&q=cinematography+filters+by+color+temperature&pg=PP1|title=Cinematography: Theory and Practice: Image Making for Cinematographers and Directors|date=2016-09-15|publisher=Taylor & Francis|isbn=978-1-317-35927-2|language=en}}</ref>

For artists, most pigments and papers have a cool or warm cast, as the human eye can detect even a minute amount of saturation. Gray mixed with yellow, orange, or red is a "warm gray". Green, blue, or purple create "cool grays". This sense of temperature is the reverse of that of real temperature; bluer is described as "cooler" even though it corresponds to a higher-temperature [[black body]].

{| style="border:1px solid #aaaaaa; background-color:white; padding:5px; font-size:95%; margin: 0px 12px 12px 0px; float: left; margin-left: 10px"
|- align=center
|colspan=2|[[Image:grays.svg|240px]]
|- align=center
||'''"Warm" gray'''
||'''"Cool" gray'''
|- align=center
||Mixed with 6% yellow
||Mixed with 6% blue
|}

[[Lighting designers]] sometimes select [[filter (optics)|filter]]s by color temperature, commonly to match light that is theoretically white. Since fixtures using [[Metal halide lamp|discharge]] type lamps produce a light of a considerably higher color temperature than do [[Incandescent light bulb|tungsten lamps]], using the two in conjunction could potentially produce a stark contrast, so sometimes fixtures with [[High-intensity discharge lamp|HID lamps]], commonly producing light of 6000–7000&nbsp;K, are fitted with 3200&nbsp;K filters to emulate tungsten light. Fixtures with color mixing features or with multiple colors (if including 3200&nbsp;K), are also capable of producing tungsten-like light. Color temperature may also be a factor when selecting [[Electric light|lamps]], since each is likely to have a different color temperature.
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