MacAdam ellipses

ellipses, MacAdam

Areas in the CIE chromaticity diagram, each in the form of an ellipse within which the colour appears the same. The size of each ellipse varies in the diagram, being larger for greens than for blues or reds. The ellipses are distorted for colour deficient individuals.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
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* Fixture-to-Fixture Color Consistency: A good metric for determining this with LED is to refer to Standard Deviation of Color Matching (SDCM) data, commonly referred to as "MacAdam Ellipses," which are named after light and color studies conducted by David Lewis MacAdam.
The LumeLEX 2024 Series is designed for the Xicato LED module, which maintains color consistency (within two MacAdam Ellipses) and intensity throughout its 50,000-hour life.
ANSI C78.377 permits white light LEDs to have variations in chromaticity within the limits of seven-step MacAdam ellipses. This may be compared with ANSI C78.376, which specifies smaller four-step MacAdam ellipses for linear and some compact fluorescent lamps.
(3) Satisfies "3-step MacAdam ellipse" color-tolerance criteria at operating temperature levels encountered during practical use (Tc = 90 degrees C).