Definition of spectral vs. colormetric data.

Could anyone give me the definitions of spectral data and colormetric data, what the differences are and maybe even how to convert one set of data to the other?
Thanks in advance!

Colorimetric refers to data that is measured or expressed in terms of tristimulus values, such as XYZ, Lab or such. If you view your measurement file in a text program and see the color information listed in anywhere between 4 - 12 columns containing usually Lab information - then your file contains colorimetric data.

Spectral data is representing color by showing wavelength values at several slices in the entire visible spectrum. So your measurement file containing something like 40 measurement fields with column headings like “nm380” is recording spectral data. The advantage of having spectral data is that your measurement can be re-purposed for different illuminants. In other words, you can roll a profile specifically for viewing under tungsten lamps, D50 daylight or any custom illuminant.

Colorimetric values can be derived from spectral data, but you can’t do it the other way around.

ColorThink Pro will convert spectral data into any of several flavors of colorimetric data: … lor_values

If you don’t have ColorThink Pro, you can use MeasureTool in the GretagMacbeth suite to convert from spectral to Lab.

We have an extensive glossary of color terms in our site that might help also: