# compute standard light spectra

### Description

Two families of standard illuminants that depend on temperature are the Planckian spectra (black-body spectra), and daylight spectra. For the daylight spectra, a smoothed version is available. Illuminant E, a third and trivial spectrum, is also available.

### Usage

1 2 3 4 5 6 | ```
planckSpectra( temperature, normalize=TRUE, wavelength=300:830 )
daylightSpectra( temperature, components=colorSpec::daylight1964,
wavelength=NULL, roundMs=FALSE )
illuminantE( power=1, wavelength=380:780 )
``` |

### Arguments

`temperature` |
a vector of temperatures, in Kelvin |

`components` |
a |

`wavelength` |
a vector of wavelengths. For |

`normalize` |
a logical value.
If |

`roundMs` |
a logical value. The original CIE method for the daylight spectra requires
rounding intermediate coefficients M1 and M2 to 3 decimal places.
This rounding is necessary to reproduce the tabulated values in Table T.1 of the CIE
publication in |

`power` |
a vector of power levels |

### Details

For `daylightSpectra`

the valid range of temperatures is 4000 to 25000 K.
For a temperature outside this range the spectrum is set to all `NA`

s.

The equations for `daylightSpectra`

and `planckSpectra`

are complex
and can be found in the **References**.

`IlluminantE`

is trivial - all constant `power`

.

### Value

For `planckSpectra`

and `daylightSpectra`

:

A **colorSpec** object with `quantity`

equal to `'power'`

,
and `organization`

equal to `'matrix'`

or `'vector'`

.
The `specname`

s are `PNNNN`

or `DNNNN`

for `planckSpectra`

and `daylightSpectra`

respectively.

The number of spectra in the object is the number of temperatures = `length(temperature)`

.

For `illuminantE`

:

A **colorSpec** object with `quantity`

equal to `'power'`

.

The number of spectra in the object is the number of power levels = `length(power)`

.

### References

Günther Wyszecki and W.S. Stiles.
**Color Science : Concepts and Methods, Quantitative Data and Formulae**.
Second Edition.
Wiley-Interscience. 1982.
page 146.

CIE 15: Technical Report: Colorimetry, 3rd edition. CIE 15:2004. Table T.1, pp 30-32, and Note 5 on page 69.

Schanda, Janos.
CIE Colorimetry, in
*Colorimetry: Understanding the CIE System*.
Wiley Interscience. 2007.
p. 42.

### See Also

daylight, `resample`

, `organization`

, `quantity`

,
materialSpectra