An RGB Solution

In practice, the user needs to specify both the desired color and intensity. This can be done using CIE xyY values, where xy represent the CIE 1931 chromaticity coordinates, and Y represents the intensity. This approach is, however, not as intuitive as the RGB settings most lighting designers are familiar with.

Fortunately, there is a simple solution. Referring to the six-color LED module color gamut shown, we can completely enclose the six-sided color gamut in a triangle defined by the xy chromaticities of virtual red, green, and blue LEDs. It does not matter that the red LED chromaticity lies outside the horseshoe-shaped spectral locus and so represents a physically impossible color. What does matter is that the RGB values can be used to represent any color (and intensity) within the six-color LED module color gamut.

Relative spectral response: Closely matches CIE Standard Observer curves x,y,z within 6% (fi') of the CIE
spectral luminous efficency V(lambda)
Cosine response (f2) EV: Within 3%
Receptor: Silicon photocell
Measuring function Tristimulus values: XYZ
Chromaticity: vay; Ev u'v'; Ev, Dominant wavelength, Excitation purity
Correlated color temperature: EVTCpA u’v’; TCp(JIS method; available only with CL-S10w)
Color difference: delta(XYZ), delta(vay), delta(Evu'v'), deltaEVAu'v'
Other function: User calibration function, Data hold function, Mufti-point measurement (2 to 30 points)
Measuring range: 0.1 to 99,990 lx, 0.01 to 9,999 fcd (Chromaticity: 5 lx, 0.5 fcd or above) in four
automatically selected ranges (lx or fcd is switchable)
Accuracy: EV (Linearity): i2%i1digit of displayed value xy: 3:0.002
Repeatability: Ev: 0.5%+1digit (2zetta); xy: $0.0005
Temperature drift: Ev: +/-3% zidigit of displayed value, xy: +/-0.003
Humidity drift: Ev: +/-3% i1digit of displayed value, xy: +/-0.003
Response time: 0.5 sec. (continuous measurement)
Computer interface: USB
Display: 2-significant-digit LCD with back-light illumination
Operating temperature: -10 to 40°C, relative humidity 85% or less (at 35°C) with no condensation
humidity range
Storage temperature: -20 to 55°C, relative humidity 85% or less (at 35°C) with no condensation humidity
range