Maybe you remember mixing paints together in art class. Add more and more pigments and eventually you can end up with a murky brown. That’s subtractive colour mixing: pigments absorb some wavelengths of light and reflect others, so mixing pigments generally leaves less light available to reach your eyes.
Additive colour mixing is different. Instead of mixing pigments, you’re mixing light. When appropriately balanced red, green and blue lights overlap, they can stimulate your visual system in a way that you perceive as white.
This is the principle behind your phone, television and computer screens. Tiny red, green and blue pixel signals can be combined at different intensities to produce a huge range of perceived colours.
The RGB Room takes this principle off the screen and puts it around you. Three spotlights project red, green and blue light onto the wall. Where all three overlap, the combined light appears white. But step in front of the lights and something strange happens: your shadow isn’t simply black. It can become cyan, magenta or yellow.
A shadow is simply an area where light has been blocked. If you block the red spotlight, for example, the wall is still receiving green and blue light. Together, these appear cyan.
So your shadow isn’t adding colour, it’s revealing the colour that remains when one of the lights is missing. The three spotlights are coming from different positions. As you move, your body blocks different amounts of each beam, so the coloured regions of your shadow change too.
You’ll also notice that the shadows can become sharper or softer depending on your position. The closer you are to the wall, the more defined the shadow will appear. The exact sharpness also depends on the size and position of the light sources.
So rather than simply showing you how red + green + blue make white, the RGB Room lets you see additive colour mixing — and its complementary colours — happening in real time.