What is RGB?

RGB stands for Red, Green and Blue. These are the three primary colours of the additive colour system. In lighting we encounter RGB for coloured lighting. RGB lighting enables you to create millions of different colours of light, all based on these three primary colours.

Additive versus subtractive colour system

The additive colour system is based on the mixing of different light colours. When two primary colours are mixed, you get a lighter colour. Mix the three primary colours (red, green and blue) and you will get white light. Unlike with paint, yellow is not a primary colour.

The best example of the additive colour system can be found in computer screens and televisions. Use a strong magnifying glass and you’ll notice that every pixel consists of a red, green and blue sub-pixel. By playing with the brightness of these sub-pixels, you can create any light colour.

The image below shows the mixing scheme of the additive colour system. It looks like this:

• Red + green = yellow
• Red + blue = magenta
• Blue + green = cyan
• Red + blue + green = white

The additive colour system is not to be confused with the subtractive colour system, which is used e.g. for print. This system is called ‘subtractive’ because less and less light is reflected when mixing colours, mixing results in darker colours. The primary colours of the subtractive colour system are cyan, magenta and yellow.

RGB lighting

RGB lighting can form all colours, ranging from warm orange to cool blue. It is often used in LED strips. In RGB LED strips we distinguish three types:

• Classic RGB: a LED strip with triple diodes (red, green and blue on one diode). To form white light, the three diodes are used simultaneously. With these classic RGB the white light may contain traces of other colours. This white light will not have the same brightness as the white light of a true white LED.
• RGB+W: A LED strip with triple diodes (red, green and blue on one diode) and a separate white diode for pure white light. Because of the larger distance between the two diodes of the same colour, evenly distributed light is not guaranteed. With this type of RGB, the distinction between the different light beams will be easier to see.
• RGBW: A LED strip with quadruple diodes (red, green, blue and white on one diode). Provides nice evenly distributed lighting in any colour.