Measuring Instruments

Giving Shape to Ideas

Precise Color Communication

Color difference ∆E*ab in the L*a*b* color space, which indicates the degree of color difference but not the direction, is defined by the following equation:
∆L*, ∆a*, ∆b*: Difference in L*, a*, and b* values between the specimen color and the target color.

The L*C*h color space uses the same diagram as the L*a*b* color space, but uses cylindrical coordinates. Lightness L* is the same as L* in the L*a*b* color space; Metric Chroma C* and Metric Hue Angle h are defined by the following formulas:
a*, b*: Chromaticity coordinates in the L*a*b* color space

For difference measurements, Metric Hue Angle difference is not calculated; instead, Metric Hue Difference ∆H* is calculated according to the following formula:

The Metric Hue Difference is positive if the Metric Hue Angle h of the specimen is greater than that of the target and negative if the Metric Hue Angle of the specimen is less than that of the target.


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