Color temperature

[1][2] Color temperature has applications in lighting,[3] photography,[4] videography,[5] publishing,[6] manufacturing,[7] astrophysics,[8] and other fields.

"Warm" in this context is with respect to a traditional categorization of colors, not a reference to black body temperature.

The fact that "warm" lighting in this sense actually has a "cooler" color temperature often leads to confusion.

Some daylight in the early morning and late afternoon (the golden hours) has a lower ("warmer") color temperature due to increased scattering of shorter-wavelength sunlight by atmospheric particulates – an optical phenomenon called the Tyndall effect.

[14] For lighting building interiors, it is often important to take into account the color temperature of illumination.

Most digital cameras and raw image software provide presets simulating specific ambient values (e.g., sunny, cloudy, tungsten, etc.)

[20] Photographic emulsion film does not respond to lighting color identically to the human retina or visual perception.

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.

More-subtle filters are needed to correct for the difference between, say 3200 K and 3400 K tungsten lamps or to correct for the slightly blue cast of some flash tubes, which may be 6000 K.[21] 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.

However, they are ineffective with sources such as fluorescent or discharge lamps, whose light varies in color and may be harder to correct for.

Common monitor color temperatures, along with matching standard illuminants in parentheses, are as follows: D50 is scientific shorthand for a standard illuminant: the daylight spectrum at a correlated color temperature of 5000 K. Similar definitions exist for D55, D65 and D75.

Windows 11 22H2 have supports for Auto Color Management (ACM) which further optimized for OLED monitors by reading EDID data.

[22] 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 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 K by using a preprogrammed setting or a custom calibration.

In this case, current versions of ATSC cite default colorimetry standards depending on the format.

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.

TVs and projectors sold in Japan, South Korea, China, Hong Kong, Taiwan and Philippines are usually adopt 9300 K as default settings.

Cinematographers 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.

[23] For artists, most pigments and papers have a cool or warm cast, as the human eye can detect even a minute amount of saturation.

Owing to their spiky distribution, much finer increments are advisable for taking measurements of fluorescent lights, and this requires more expensive equipment.

The CIE 1931 x,y chromaticity space, also showing the chromaticities of black-body light sources of various temperatures ( Planckian locus ), and lines of constant correlated color temperature
The black-body radiance (B λ ) vs. wavelength (λ) curves for the visible spectrum . The vertical axes of Planck's law plots building this animation were proportionally transformed to keep equal areas between functions and horizontal axis for wavelengths 380–780 nm. K indicates the color temperature in kelvins , and M indicates the color temperature in micro reciprocal degrees.
Approximation of the hues of the Planckian locus as a function of the kelvin temperature, rendered with a white point near 6500 K, not accounting for chromatic adaptation
Color temperature (right) of various light sources (left)
Color temperature comparison of common electric lamps
Color temperatures of common electric lamps
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.
Log-log graphs of peak emission wavelength and radiant exitance vs black-body temperature, plotted on the blue line. Red arrows show that 5780 K black bodies have 501 nm peak wavelength and 63.3 MW/m 2 radiant exitance.
Characteristic spectral power distributions (SPDs) for an incandescent lamp (left) and a fluorescent lamp (right). The horizontal axes are wavelengths in nanometers , and the vertical axes show relative intensity in arbitrary units.
Characteristic spectral power distribution of an A0V star ( T eff = 9500 K, cf. Vega ) compared to black-body spectra. The 15,000 K black-body spectrum (dashed line) matches the visible part of the stellar SPD much better than the black body of 9500 K. All spectra are normalized to intersect at 555 nanometers.