Colour consistency is critical to a good looking LED-based installation. ‘White’ light comes in a range of shades, and ‘white’ LEDs can vary in colour appearance. This is not just in the normal warm-cool range, but even at a given CCT different colour qualities can lend slightly different tints to the light source appearance.
Controlling this appearance is a key concern to Luxonic. One way of quantifying the colour appearance variation is to use steps of ‘just noticeable difference’ as determined by a human observer in controlled conditions.
These standardized steps, also known as ‘MacAdam Ellipses’ or ‘SDCM’ can be used to specify colour consistency. In a real-world installation anything better than 3-steps is considered imperceptible, with 5-steps being ‘the norm’.
Luxonic is proud to offer single colour binning for LEDs, equating to a 2-step initial consistency (3-step through life)
The following three graphics illustrate the relationship between a single colour consistency bin (orange quadrangle) and a range of MacAdam step tolerances (blue ellipse):
A single-step MacAdam ellipse represents the limit of perception for colour differences in a side-by-side, laboratory style comparison. Here, it can be seen that even the tightest manufacturing tolerances (a single bin supply) will include LEDs with colour variations that can be perceived in the most closely scrutinised situations.
A two-step MacAdam ellipse is a very close match to a single bin, and could reasonably be described as equivalent. Although a single bin may have LEDs with colours at tolerance extremes, in practice LEDs are not used individually and a whole-luminaire colour appearance will always be close to the centre of the quadrangle.
A three step MacAdam ellipse is generally accepted as ‘imperceptible in a normal installation’. Single bin supply between luminaire batches and models is the most reliable way of ensuring unquestionable colour consistency within a lit environment.