Measuring color with the MacAdam Ellipse

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.

Let’s say you drive by two gas stations. Station A is illuminated throughout by bright white LEDs, while Station B’s lights vary from yellow to white and one panel is dim. You will likely go to Station A because its color consistency feels comforting and high quality, even if you aren’t conscious of that decision.

The difference in color between two lights is defined by an industry-specific standard called the MacAdam Ellipse. 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.