Measuring color with the MacAdam Ellipse

Most of human sensory information is visual, coming to us through reflected light. Color consistency describes the non-variation in color from light source to light source, and fixture to fixture. We often don’t realize that we are influenced by the uniformity of color, but we always respond to it.

In real life, our eyes respond to very subtle differences in color, for example, you may easily notice one pixel (or a few) on your laptop screen is in slightly different color than the rest of area of same color on the screen. The smaller the color differences are, the more uniform the light is. In LED lighting, the less difference of the color is from each LED, the more uniform or pure of color your eyes will tell you. Pure color or image usually provide a sense of high end, luxury and comforting.

The difference in color between two lights is defined by an industry-specific standard called the MacAdam Ellipse chromaticity diagram. Each time the human eye can detects a color shift, it is measured as a MacAdam Ellipse step. In a range of 7 steps, the smaller the step, the more consistent lights are in color. By ANSI standard, step 5 to step 7 is acceptable for light sources for general lighting purposes.

Homogeneity of LEDs is often defined in MacAdam Ellipses. By MacAdam’s definition, 1-step binning means “differences are not visible”, 2 & 3-step binning means “differences are not or hardly visible while 4-step binning means “differences are visible. A 1116 ANSI binning can be described by a 3-step MacAdam Ellipse and is currently the smallest binning offered by ELD manufacturers. Another term used for homogeneity of LEDs is SDCM Scale (Standard Deviation of Colour Matching).

Many of our products use LEDs that are within MacAdam Ellipse step-3 which is usually required by high-end lighting. For more information, please go to https://www.beyondled.com/strip-lighting.