Ask the Expert Question-and-Answer Archive

by Ron Joseph

June, 2005

Converting Color Specifications to Pantone

Q. I'm part of an ASTM group that is writing a standard to specify icons designating safety of items in and near MRI scanners. We would like to reference the colors for safety signs given in ISO 3864-1. These colors are given in DIN, RAL, Munsell, AFNOR, and NCS systems. I would like to specify a corresponding Pantone for each color. Can you tell me how to determine the equivalent Pantones?

The colors are red, yellow, green, white, and black. The RAL specifications are: RAL 3001,RAL 1003,RAL 6032,RAL 9003, and RAL 9004, respectively. The Munsell specifications are: 7,5R 4/14 ; 10YR 7/14; 5G 4/9 ; N 9,5 ; and N 1, respectively.

I'd greatly appreciate any assistance you can provide. Thanks!!

A. Your e-mail was referred to me by Ron Joseph.

The Pantone system is not a color system like the NCS or the Munsell color systems, but a colorant system. Because of this, you do not have "numbers" for all possible colors, and exact equivalents are the exception, not the rule. The fact that RAL CLASSIC, a system much older but similar to Pantone, is already specified may be due to a selection done the other way around, where the RAL patches

Here are a two possible ways to try finding a match:

Method 1: Using "good quality" or "certified" RAL (or Munsell) patches, measure them with a spectrometer that can be used with software which has Pantone chips libraries. Companies such as X-Rite and GretagMacbeth offer such packages. For example, using the GretagMacbeth Eye-One spectrometer and the Eye-One Share software, the closest Pantone chip is automatically selected when a sample is measured; you can also determine the color

Method 2: Using an add-on plug-in sold by the RAL organization, select the RAL CLASSIC patch in a graphics editing program which offers a Pantone chips picker, such as Photoshop. When a RAL patch is selected, you get its equivalent L*a*b* D50 coordinates. Then, using these coordinates, find the nearest Pantone chip with the program color picker. Caveat: L*a*b* data is rounded to the nearest integer in Photoshop. The link for the RAL plug-ins is: http://www.ral-digital.de/english/ral-liste_e.htm

I would also check the matching accuracies between the known RAL and Munsell chips as a guide of what would be

Please keep us informed of your progress,

Regards,

Danny Pascale