TECHNICAL NOTE10 MIN · 08 JUN 2026
3-Step MacAdam Ellipse: why LED binning makes or breaks white walls
D
Devang M.
Head of Optical Engineering
When five downlights cast three different shades of warm white on the same gypsum ceiling, binning tolerance is the culprit.
Human eyes are extraordinarily sensitive to relative color discrepancies when two light sources illuminate adjacent segments of the same neutral white wall.
Standard Deviation of Color Matching (SDCM)
A 1-step MacAdam ellipse represents the threshold where most observers cannot detect any color variation. A 3-step ellipse represents the maximum allowable variance for architectural grade fixtures.
Cheap commercial fixtures use 5-step or 7-step binning, resulting in noticeable pinkish or greenish hue shifts between supposedly identical 3000K fittings.
Key Engineering Takeaways
- Insist on SDCM ≤ 2-step for high-end residential and gallery projects.
- Color consistency is maintained through single-bin sorting at the semiconductor packaging phase.