Colourmixing With RGB LEDs

Published : 2015-01-28 00:01:38
Categories : Lighting Basics

Colourmixing With RGB LEDs

Colour mixing LED's allows you to create virtually any colour from the three primary colours of red, green and blue (generally shortened to RGB). That's not a mistake, when dealing with light, the primary colours are red, green and blue, not red, yellow and blue as it is with pigments. The colour mixing is achieved by dimming each colour to create resultant colours. If using a system such as DMX (like our range of dimmers), which would allow each colour to be set between 0 (off) and 255 (full brightness), you can potentially create up to 16,777,216 colours (though keep in mind that many of these will simply be the same colour at different brightness levels, which, while strictly speaking are not unique colours, can still be quite useful).

So what mix of the primary colours do you need to make a specific colour? Most people learn from early on how to mix pigments (ie paint) to get the colours they desire (eg blue and yellow make green). Not quite so many people are familiar with mixing light, though it does work in very much the same manner.

To give an idea, the secondary colours are >

  • Red & Green               = Yellow
  • Red & Blue                  = Magenta
  • Green & Blue               = Cyan
  • Red, Green & Blue      = White

It would take a rather large table to list every possible combination, so instead, try the RGB colour calculator to see how to create various colours. Keep in mind there are a number of reasons why what you see on your screen may not match the output from a LED installation. To start with most people's monitors aren't adjusted to produce a true colour representation.

The second factor is obviously the LED installation itself. Factors here can include:

  • The exact colour of the LED (just what green is that green LED?). This is where the binning can play such an important part;
  • The distance between the LEDs and the surface;
  • How closely the different coloured LED dies are placed, along with their direction; and
  • The colour of the surface being illuminated.

Note the distinction here between a LED and a LED die. The LED die is the actual light emitting part while the LED describes the entire package, which may include several dies. LEDs that incorporate a red, green and blue die (such as the LEDs used on the Harlequin RGB LED strip and the 3W Taipan RGB LED Luminaire), position the dies as close as possible, meaning the colours will mix in a shorter distance, and your installation will have fewer colour stripes or spots.

With this knowledge, you can set about creating some highly impressive and dynamic LED installations

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