We perceive colours in different ways. There is a joke about the arguing married couple in the wallpaper store. The husband claims there exist only eight colours, and that the wife’s lime, turquoise, aquamarine, emerald, olive and pistachio all are green. Evidently they have different eyes regarding colours and colour temperatures.
When it comes to Christmas illumination there are similar disagreements, yet with the white colour in focus. What is really white? White as an A4 paper, cold white as a fluorescent lamp, or warm white as a candle?
At Christmas time, most people prefer a warm glow around their homes, while at shopping centers you can often see an icy, almost blue light from the decorations of the facades.
CIE, RGB and black bodies
As a producer and buyer of LEDs, it is important to not only understand what fits where, but also to be able to specify for the diode factories exactly what colour the light should have. So here are the basics for this:
The CIE triangle is an empirical colour concept or rather an agreement from 1931. It is related to the wavelength range 380-750 nm and the visible red green blue (RGB)… ehum.. the man in the wallpaper store was right after all ..!?
However, it is not enough to just define the X and Y values. You have to keep in mind the black body curve too! (Planckian locus)
Colour temperature means the light that is created when you heat a black body to a certain temperature. Imagine that you heat a piece of metal to 2000 degrees (2000 C = 2273 K). Then its glow will have a colour similar to a candle glow (warm white, yellowish tone). If you put on more heat, up to eg 10,000 degrees, the colour will be colder, almost blue. When you specify an LED, it is therefore not enough to specify the colour temperature, you must also enter X, Y in order not to get any major deviation from the black body curve.
Color temperature
On the boxes for LED lights you will in general find color temperatures indicated according to the following approximate scale:
| WARM WHITE | – 3300 K |
| WHITE | 3300-5300K |
| COOL WHITE or COLD WHITE | 5300K – |
For Montejaur FLAGPOLE CHRISTMAS TREES and LED CHRISTMAS TREES, we strive to be at the “true” 2700K for warm white and 6000K for cold white. 2700K gives a neutral but warm light, without excessive and tasteless yellow tone. With the correct formula, ie close to the black body curve, you avoid deviations towards pink or other colors.
If you want to perform your own tests, there are apps available which highlight colour charts vs temperature. You can then make your own visual estimate, however with a most often unacceptable uncertainty. Errors in the range of 1000K are possible. For a more accurate study, a real colourimeter is required, however these cost just over 2500 eur.
To sum it up, it might be cheaper to redo the wallpapering.
