Working with Spectral Colors

Color lists containing spectral measurement values are much more powerful than those that containing only colorimetric Lab / XYZ values. Colorimetric values are obtained by combining spectral measurements with spectral illuminant (lighting) curves and standard human observer curves. By altering the illuminant and observer curves, the appearance of the measured samples can be simulated under different lighting and observer conditions. For example, the appearance of a measured color patch can be calculated first under D50 and then under incandescent lighting to see how much of a color shift will occur when the patch is moved between the lighting conditions.

Recognizing Spectral Colors

When ColorThink reads spectral data for a color, the color patch in the list will contain a thumbnail of the actual measured spectral curve. Use this curve to discriminate between spectrally-defined colors and those from Lab measurements or the result of profile calculations.

Opening the Color Setup dialog

Select Color Setup... from the list popup menu above the desired list.

Selecting an Illuminant

Choose a built-in illuminant from the ‘Illuminant’ popup in the Color Setup dialog box. Additional illuminants may be opened from the popup using the Open option. ColorThink currently recognizes illuminant data saved in the CGATS text file format. For an example of a custom illuminant, click here.

Selecting an Observer

Choose either the 2° or 10° Standard Observers in the Color Setup dialog box. These observer curves correspond to the 1931 and 1964 human observer values from the CIE.

All selections in the Color Setup dialog occur in real-time so if you have the delta-E calculations enabled or the colors displayed in the Grapher you can see your colors change immediately.

Try out the "Evaluate Device Tone Stability" procedure in the ColorSmarts Guide for a practical example of this feature.