Instructions
The library contains spectral data from light sources such as the Incandescent, Fluorescent, and LED Lamps.
Some are measured using spectrometers, standardization organizations define others, and some are calculated from mathematical models.
This app shows all the available illuminants in the form of their spectral distributions and primary colorimetric data.
Output
At start-up, the CIE F1 illuminant data are displayed.
Its spectral distribution and name, Correlated Color Temperature, CIE Color Rendering Indices Ra and R9, and IES TM30 Rf and Rg are shown on top.
Correlated Color Temperature is given with unit Kelvin and includes a Tint value, with a unit of 1 corresponding to a distance of 0.001 in the CIE 1960 (u,v) color space.
The CIE F1 illuminant, for example, has a correlated color temperature of 6425 Kelvin.
It has a Tint of +7Δ, which means it is located above the Planckian locus, with a more blue/cyan-ish color than a Planckian radiator would have.
Its general color rendering index Ra value is 76, and its R9 value is -47.
The R9 value indicates how well a source renderers deep red, an essential element of skin color, being the color of blood.
A value of -47 is not very good; a value of at least 0, but preferably 20 or higher, is required if you want people to look not sick with your chosen light source.
Developed by Illumination Engineering Society (IES) members, TM30 is a new standard to evaluate a light source’s color fidelity and gamut.
The F1 illuminant, for example, has a color fidelity Rf value of 81 and a gamut area index of Rg of 90.
The Rf value is obtained from 99 instead of 8 test samples, as used for the CRI calculation, and is a better prediction of color rendering performance.
The Gamut Area Index represents the ability of a light source to enhance colors in a scene: colors look more vibrant if this value is above 100.
The CIE LED-RGB1 illuminant, for example, has a gamut area of 107.
Source Selection
Below the plot is the source selection area.
The sources are grouped into different collections; currently, there are the “CIE” and “IES” collections.
Select a collection by clicking on the first tab of the light source list.
At start-up, the “CIE” collection is chosen.
Select a category within the library with the second tab.
The available classes vary with the source library but typically describe the emission type of the sources, such as Fluorescent, Incandescent, High-Intensity Discharge, and LED.
The illuminant within a category is selected by clicking one of the source buttons.
The currently selected button is highlighted.
Access Spectral Data
The spectral data can be copied to your device’s clipboard by clicking the spectral plot area.
A regular click will copy the data as two columns of values, with wavelengths, in nanometer units, in the first column, and spectral values in the second column.
The values can be directly pasted into a spreadsheet if you want to do calculations yourself.
Spectral values are normalized to a peak value of 100.00 and are given with a three-decimal precision.
Holding down the “shift”-key while clicking the spectral area will copy a single column of spectral data over a range from 380 to 780 nanometers, with a step size of 1 nanometer, resulting in a total of 401 copied values.
Troubleshooting
You must be online to use this app, as the spectral data are fetched from the website when selected.
Please check your internet connection if you don’t see any spectral plot or sources in the list.
The site uses JavaScript, as many web apps do nowadays, but if you have disabled JavaScript support for this site, you need to enable it to use its functionality.
CIE Standard Illuminants
These are identified by one or more capital letters followed by zero or more digits.
Typically, these sources, such as the equal energy E-illuminant, don’t exist in physical form and are mainly used for colorimetric research and as references.
Fluorescent (F-series)
The fluorescents here are distinguished by narrow-band and broad-band categories, referring to the spectral width of the phosphors used.
F1-F6 fluorescent lamps emit two semi-broadband wavelengths of antimony and manganese activations in calcium
halophosphate phosphor. F7-F9 are broadband fluorescent lamps with multiple phosphors and higher CRIs.
At the same time, F10-F12 are narrow triband illuminants that emit three narrowband wavelengths in the visible spectrum’s R, G, and B regions.
High-Intensity Discharge (H-series)
The CIE defined five High-Intensity Discharge Standard Illuminants types using the letters H1-5.
LED
LED Standard Illuminants are defined as mixtures of Red, Green, Blue, Amber (RGBA) LEDS, Phosphor Converted (PC) LEDs, and combinations of both types (Hybrid).
Five blue-pumped phosphor illuminants (B1-B5), two violet-pumped phosphor LEDs (V1-2), one RGB LED (RGB1), and one blue-pumped hybrid (BH1) LED Illuminants were defined.
Other
The A illuminant represents a tungsten filament lamp with a spectral power distribution similar to a Planckian radiator with a temperature of approximately 2856 Kelvin.
Historically, illuminants B and C were defined as physical standards obtained from an A illuminant using liquid filters to represent daylight.
They are not commonly used anymore and are included here for historical reasons only.
Four specific daylight illuminants are defined, denoted by the codes D50, D55, D65, and D75, for daylight with correlated color temperatures of approximately 5000, 5500, 6500, and 7500 Kelvin.
IES TM30 Source Library
A team of scientists used the sources in this library to develop new metrics for light source color rendition, as described in a technical memorandum published by the Illuminating Engineering Society in 2015 and revised in 2018 and 2020.
The collection at this site contains 318 spectral distributions.
They are listed here using categories similar to the CIE standard illuminant library.
It includes some CIE standard illuminants, actual measured spectral distributions, and spectral distributions based on mathematical models, such as distributions containing a mixture of Gaussian components balanced to a particular color point.
Fluorescent Broad-Band
Besides the CIE Standard Broad-Band Illuminants, this library adds measurements of 17 fluorescent lamps, primarily linear fluorescents, with different lengths, diameters, color temperatures, and color rendering indices.
The naming of Fluorescent lamps varies a bit by market and manufacturer, but typically, the first two numbers after the letter F indicate lamp power in units of Watts.
Diameter, in units of 1/8 inch, follows after the letter T.
Other letter combinations follow, with CW and WW, indicating Cool and Warm White color temperatures, and C75, a color temperature of approximately 7500K.
For example, other letters indicate a Rapid Start (RS) lamp or the letter X for _De Luxe variants for better color rendering.
Fluorescent Narrow-Band
This category includes many more fluorescent lamps, combining three phosphors.
Here, a code such as 735 indicates an illuminant with a CRI/Ra value of 70 and a color temperature of 3500K; a lamp with code 850 has a minimum CRI of 80 and a CCT of 5000K.
High-Intensity Discharge Lamps
Incandescent Lamps
Hybrid RGB(A)/PC LEDs
RGB(A) LED mixtures
Phosphor Converted LEDS
Mathematical Distributions
Other Lamps