From Wakapon
Black Body
In terms of frequency (<math>\nu</math>) or wavelength (λ), Planck's law is written:[1][2][3]
- <math>B_\nu(T) = \frac{ 2 h \nu^{3}}{c^2} \frac{1}{e^\frac{h\nu}{k_\mathrm{B}T} - 1},</math> <math>\text{ or }\,</math> <math>B_\lambda(T) =\frac{2 hc^2}{\lambda^5}\frac{1}{ e^{\frac{hc}{\lambda k_\mathrm{B}T}} - 1}</math>
(source http://en.wikipedia.org/wiki/Planck%27s_law)
RUFF STUFF
CCT = Correlated Color Temperature (6500K, etc.)
CIE Illuminants =>
- General lighting conditions (when taking a picture, or displaying one).
- Spectral characteristics similar to natural light sources
- Reproducible in the laboratory
1931 Illuminants:
- Illuminant A = Typical Incandescent Light
- Illuminant B = Direct Sunlight
- Illuminant C = Average daylight from total sky (ambient sky light)
1963 D Illuminants (more accurate daylight conditions):
- Illuminant D = Phases of daylight. Necessarily followed by the first 2 digits of the CCT (e.g. D65 = D 6504K)
- Represent daylight more completely and accurately than do Illuminants B and C because the spectral distributions for the D Illuminants have been defined across the ultraviolet (UV), visible, and near-infrared (IR) wavelengths (300–830 nm).
- Most industries use D65 when daylight viewing conditions are required
- D50 is used by graphic arts industry => more spectrally balanced across spectrum
Other illuminants:
- Illuminant E = Equal energy illuminant
- Illuminant F = Fluorescent lamps of different composition.