The camera lens sends light to a set of special mirrors, which reflect light of a given colour but allow through other colours. The light is thus split into its components of red, blue and green. These are taken to separate camera  tubes, which produce signals from each of these colours. These are processed in terms of brightness, hue and saturation. These three signals are broadcast on one carrier wave. At the receiving end of the TV set, the three signals are separated and processed to  reproduce the signals for red, blue and green.  These are applied to three guns in one CRT. The screen is made up of thousands of phosphoric dots, each one third of which emit one colour. The dots are arranged in groups of three, one for each colour. There is a perforated metal mask between the dots and the screen. There is alignment between the perforations with each triangular group. The respective guns fire at respective dots. Thus the scene is reproduced in its true colours.