What is the difference between CIE F11 and TL84 illuminants?

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FAQ: “I am struggling in getting the difference/definition of TL84 and F11. As far as I understand F11 is defined by CIE, correct? I have found a couple of references mentioning TL84 to be equal to F11. However I get different results in EasyMatch QC comparing data for both illuminants. Can you help me explaining the difference and definition between CIE F11 illuminant and TL84?

A CIE illuminant adjusts the color values to reflect what the product looks like under different types of white light sources or lamps.

A CIE illuminant is a table of numbers that represents the spectral output of a given type of white lamp in the visible spectrum.

CIE F11 illuminant represents a narrow tri-band fluorescent of 4000° Kelvin color temperature, CRI 83.

This is a category of fluorescent lamps with narrow tri-band phosphor construction with a 4000° Kelvin color temperature that can be made by several lamp manufacturers.

The CIE illuminant is the average SPD spectral power distribution measurement of several lamps of this type from as many manufacturer that make this type of lam and codified into a standard illuminant table format.

TL84 represents a Philips narrow tri-band fluorescent lamp (4000° Kelvin, similar to CIE illuminant F11) typically found in Marks & Spencer stores in Europe. The SPD spectral power distribution measurement is based on this specific TL84 lamp product provided by a single manufacture - Philips, in this case. We call this a custom illuminant. TL84 is not the official CIE illuminant table but would be similar if not near-identical to CIE F11.

Philips is the largest manufacturer of this type of lamp and you can be assured it was well represented in the CIE F11 illuminant SPD measurement definition.

If you were a retailer with Philips TL84 lamps throughout your stores, a case could be made that using TL84 might make your calculated color values better reflect the color of products being sold in those stores.

In practice, CIE F11 and Philips TL84 illuminants are similar. The difference in color values calculated using F11 and TL84 should be very close in absolute values and would agree in differences.

It is most important that the customer report which illuminant was used in the calculation of their reported color values when they communicate with other sites.

More info in the enclosed reference:

http://www.hunterlab.se/wp-content/uploads/2012/11/Equivalent-White-Light-Sources-and-CIE-Illuminants.pdf

 

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