Thin Film Design & Applications  

MacAdam Ellipses

History: In the early 1940's Dr. David MacAdam tested the threshold sensitivity of the eye to chromaticity differences in the matching of colored lights.  MacAdam found that the threshold could be described with ellipses on the chromaticity diagram.  The ellipses calculated on this page represent the matching results of one observer.

Benefits: The MacAdam Ellipse can help coating manufacturers quantify color coatings, by measurement, for their similarity in color to inspection standards.  This is a very helpful tool for the coater operator.  It gives the operator an indication if the run is within tolerances before the parts get to a visual inspector.  As we all know, visual inspection is at the mercy of individual interpretation for color.  Most color witness samples cannot possible cover all spectral combinations that could come out of a coating run.  And some color samples that have been coated with less energetic processes (resistive or low temperature e-beam) can shift with environmental conditions.  Therefore it is important from a quality standpoint that  every standard can be traced back to measured chromaticity coordinates.  MacAdam Ellipses help to define the boundary on the Chromaticity Diagram where color will start to appear dissimilar from the ideal.


g11 plot

2g12 plot

g22 plot

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