All "WHITE" on the night?

Colour Point Consistency & The Binning Process

The colour rendering issue can be resolved by extending the CRI test. Conventional testing (of fluorescent sources and other discharge lamps) uses an 8-colour point reference system to assess colour accuracy. This has been shown to be unreliable for LEDs, which need a 9-point - or possibly even a 15-point system of measurement.
Colour Point Consistency needs to be tightened. This is all about reducing the acceptable tolerances in colour deviation between chips. The MacAdam Ellipse and SDCM (Standard Deviation of Colour Matching) that are used in these kinds of assessments - suffice to say that elements within the LED industry are calling for a maximum of 2-3 SDCM/MacAdam steps, which is described as 'hardly any colour difference visible'

NOTE: Only 1 SDCM/MacAdam step means that there is no colour difference between chips. Greater than 4 SDCM/MacAdam steps is defined as there being a 'colour difference visible'.

What is the Binning Process?

•An additional consideration is that the process for producing LEDs cannot accurately reproduce them with identical colour appearances, especially for white LEDs.

•To overcome this a process called binning is used, in which the LEDs are sorted into groups of similar colour appearance.

•The level of precision required depends upon the application. Basically, the shorter the throw of the light before illuminating a surface or where numerous light sources are in the field of view, the more critical the binning.

•Hence, for an application such as wall washing, it’s essential for all the LEDs to match closely to give a consistent appearance.

•However, if floodlighting a statue with one or two projectors from an adjacent building the binning process is less important, as individual differences would be less obvious

Binning practices need to be standardised across the industry, especially as we are seeing a burgeoning replacement lamp sector and we can easily imagine LED lamps from one source being installed alongside another. 

various sources contribution to information.