Maintaining colour consistency in LED lightings and light source has always been a challenge. It seems strange that we cannot maintain consistent lighting color tone for a machine made hardware.
After producing the LED chipsets, they are stored or group together in different bin. Each bin can be sorted by different methods, one being how close they are of the same colour tone.
With the variable nature of the colour produced by white light LEDs, one commonly used metric for expressing the extent of the colour difference within a batch (or bin) or LEDs is the number of SDCM (MacAdam) ellipses steps in the CIE colour space that the LEDs fall into.
In this situation as a manufacturer and LED Lighting OEM specialist, we can minimise inconsistent LED lighting colour tone by relying on SDCM (Standard deviation colour matching) or MacAdam Ellipse when selecting the LED chipset to be used in our lighting products.
If the chromaticity coordinates of a set of LEDs all fall within 1 SDCM (or a “1-step MacAdam ellipse”), most people would fail to see any difference in colour. If the colour variation is such that the variation in chromaticity extends to a zone that is twice as big (2 SDCM or a 2-step MacAdam ellipse), you will start to see some colour difference. A 2-step MacAdam ellipse is better than a 3-step zone, and so on.