Relationship between color temperature and wavelength

visible light - Is Color Temperature and Wavelength the Same Thing? - Physics Stack Exchange

relationship between color temperature and wavelength

The relation between color and temperature: Wien's Law. brightest (is most intense) at a wavelength (in meters) tex2html_wrap_inline In the winter constellation of Orion, a beautiful contrast is seen between the red the color variation of stars is a direct consequence of their surface temperatures. relationship between the temperature of a blackbody, and the wavelength of. If you need only one wavelength (or light in the range around a single I'm trying to understand the correlation between color temperature and.

Color temperature

The farther a wavelength is from the peak, the less power the light with that wavelength will have. As a blackbody gets hotter, the peak shifts toward shorter wavelengths.

relationship between color temperature and wavelength

At this point you should stop reading and play around with one of the excellent interactive diagrams which show the change in the spectrum of the emitted radiation as you vary the temperature. See Resourcesbelow. An incandescent lamp is very nearly a blackbody radiator, and the distribution of power in the wavelengths it produces can be described by the temperature of a blackbody radiator whose light would appear to the human eye to be of the same color.

Star Colors and Temperatures

So a typical watt incandescent has a color temperature of K. Photoflood lights, however, are either K or K. A black body can be described by its color temperature, whose hues are depicted above. By analogy, nearly Planckian light sources such as certain fluorescent or high-intensity discharge lamps can be judged by their correlated color temperature CCTthe color temperature of the Planckian radiator that best approximates them.

relationship between color temperature and wavelength

For light source spectra that are not Planckian, color temperature is not a well defined attribute; the concept of correlated color temperature was developed to map such sources as well as possible onto the one-dimensional scale of color temperature, where "as well as possible" is defined in the context of an objective color space. Background[ edit ] Judd's r,g diagram. The concentric curves indicate the loci of constant purity. Planckian locus in gray. Translating from trilinear co-ordinates into Cartesian co-ordinates leads to the next diagram.

Judd calculated the isotherms in this space before translating them back into the x,y chromaticity space, as depicted in the diagram at the top of the article.

The relation between color and temperature: Wien's Law

Note the even spacing of the isotherms when using the reciprocal temperature scale and compare with the similar figure below. The even spacing of the isotherms on the locus implies that the mired scale is a better measure of perceptual color difference than the temperature scale. The notion of using Planckian radiators as a yardstick against which to judge other light sources is not new.

Raymond Davis published a paper on "correlated color temperature" his term. Judd published a paper on the nature of " least perceptible differences " with respect to chromatic stimuli.

The influence of different wavelengths of light on human biological rhythms.

Empfindung" German for sensation was proportional to the distance of the colors on the chromaticity diagram.

Therefore, we can define the color temperature of a light source as the value of the absolute temperature of a black body radiator when the radiator chromaticity matches that of the light source. In the case of fluorescent lamps that can only approximate the chromaticity of a black body, the corrected term "correlated" color temperature is applied through a calculated chromaticity.


The color temperature chart below Figure 2 illustrates the range of colors generated by both inside artificial and outside natural sunlight lighting. Values falling below K are generally considered to be in the "tungsten" range and neutral colors viewed under this illumination often appear more red that they do under natural daylight. The concept of color temperature is very important in the photography arena, where film emulsions must be balanced to accurately render color using different light sources.

For instance, films intended to be used outside in ordinary daylight, fluorescent, and flash lighting are balanced during manufacture for a color temperature of K while films made for indoor tungsten light bulb use are balanced for a color temperature of to K.

The K average daylight color spectrum varies during different parts of the day. In the early morning and late evening, the color temperature will fall to K and lower causing color shifts in the emulsion resulting in warmer redder color rendering.