As children, we learnt that red, yellow and blue paint can be mixed to form other colours – so why do visual displays rely on red, GREEN and blue?
The answer is based on how the colour-sensing cone cells in our retinas detect the differences in wavelength corresponding to different colours of the visible spectrum. Each of the three types of cone cells is most sensitive to a different area of the spectrum. Specific wavelengths stimulate the cells in different combinations of intensity, and these combinations are interpreted by the brain as colour.
True colours – or not?
The additive RGB colour model leverages this effect to form the basis for the overwhelming variety of electronic colour displays, from colourful light strips to TVs, computer and surveillance monitors, and signage displays. By varying how brightly each of the red, green and blue channels shine, the combined wavelengths can stimulate the eye in literally millions of ways.
Hack the spectrum
An Arduino compatible RGB module is controlled by a PWM (pulse width modulation) signal to selectively illuminate each of the elements, which share a common cathode or common ground. This lets you add light that will be seen as any colour you like to your next project.