SDCM or MacAdam ellipse is standard deviation of color matching. A chromaticity plot, shows that each color can be formed by a red-green-blue blend and has its own unique number in the chart. Thanks to this, a given color can be represented by an ellipse surrounding the indicated point. The area indicated in the diagram includes color discrepancies that are indistinguishable to the human eye compared to the color inside the ellipse. SDCM is defined as the range of an ellipse around a blackbody, and the smaller the multiplication of the ellipse, the greater the coherence of the light color.
The MacAdams measure also indicates the sort level. LEDs by their "nature", at the production level, differ in color temperature, although they are made to the same specifications. If we want to obtain a homogeneous lighting installation using many luminaires, the LEDs cannot differ significantly from each other. The way to solve this problem is sorting the LEDs according to the scale from the SDCM module. The lower the index, the the color temperature is closer to the original color:
- 1 - 3 is used in places that require uniform color quality
- 3 - 5 with general interior lighting
- 5 - 7 are designed for outdoor environments and products with lower quality requirements.