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Ask the Expert Question-and-Answer Archive

by Ron Joseph

October, 2005


Q. In February of 2005 you were asked: Converting RAL and Pantone colors to CIE Color Coordinates. The web page did not come up when I clicked on it. Do you mind once again answering how to convert Pantone colors to CIE color coordinates? Thanks.

A. Your question was referred to me by Mr. Ron Joseph.

CIE color coordinates encompasses many different color spaces, such as xyz, xyY, XYZ, L*a*b*, L*u*v* that can be determined for various illuminants (Illuminant A, D50, D65, etc.) and Standard Observers (2 degrees (1931) or 10 degrees (1964)).

Even with all the possible combinations of color space, Illuminant and Observer, L*a*b* values computed for D50 and the 2 degrees Observer are the most frequent, and often the only, equivalents found for Pantone chips.

Here are a few methods to obtain the data:

1- Using a software package that supports Pantone color libraries, such as Adobe Photoshop, select the Pantone chip you are interested in using the program color picker. Within the color picker, the selected color can be seen in L*a*b* (D50, 2 degrees). However, if you need L*a*b* data for another illuminant, D65 for example, you need a dedicated color conversion software. Also, if you need data for a 10 degrees Observer, often used in the paint world, you need to look at method 3 below.

2- Purchase a dedicated colorimeter from Pantone which finds the closest Pantone chip to a measured color, and which also gives its L*a*b* equivalent. Note: This colorimeter is NOT a general purpose colorimeter and will only suggest the nearest match, not the exact measured value. For data with different Illuminants or the 10 degrees Observer, the comments of method 1 also apply.

3- Purchase a colorimeter or spectrophotometer which can provide almost any CIE type data for any measured color. Typical colorimeter: Konica Minolta Chroma Meter (usually provide data for Illuminant C and D65, 2 degrees Observer) Typical spectrophotometers: GretagMacbeth Eye-One, X-Rite Pulse, as well as equipment manufactured by HunterLab, Barbieri Electronic, and many other companies.

For more information on how to obtain CIE data from a measured color spectrum, you can have a look at a series of articles I wrote and which were published in the Metal Finishing magazine:

Finally, while it is relatively easy to find an exact CIE equivalent to any Pantone chip, the reverse is not. This is due to the fact that Pantone is a colorant system and not a universal color system.

Danny Pascale

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