Three colours, several million times
How Does a Television Make a Picture?
A screen holds no pictures — only millions of tiny red, green and blue lights, each told how bright to be.
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Step 1 of 5
Up close there are only dots.
What looks like a smooth image is a grid of separate lights. Your eye blends neighbours together long before it can pick any single one out.
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Step 2 of 5
Three colours are enough for all of them.
Your eye has three kinds of colour detector. Mixing red, green and blue light in the right proportions fools all three the way a real colour would.
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Step 3 of 5
The signal is a list, not a picture.
What arrives is numbers: how bright each dot should be, in order, over and over. The set's job is to turn that list back into light.
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Step 4 of 5
Every dot is switched, not painted.
An LCD holds a backlight behind a shutter for each dot; an OLED makes each dot glow on its own. Either way, nothing moves across the screen.
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Step 5 of 5
Motion is your eye being slow.
The whole grid is redrawn dozens of times a second. Nothing on the screen ever moves — it is a flipbook fast enough that you cannot see the flips.
A 4K screen has 3,840 × 2,160 dots — about 8.3 million — and each needs a new red, green and blue value 60 times a second.
The short version
A television makes pictures from millions of red, green and blue dots, each given a fresh brightness dozens of times a second.
Try it yourself
Put a drop of water on a switched-on screen. It acts as a lens and the three coloured stripes inside one dot become visible.
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