Millions of tiny lights
Why Are Pictures Made of Dots?
A screen holds no pictures, only a grid of dots that each change colour.
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Step 1 of 5
A screen holds no pictures, only dots.
The grid never moves and nothing is ever drawn on it. Each fixed dot simply takes a new colour, and your eye assembles a picture from them.
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Step 2 of 5
Each dot is really three lights.
Look closely enough and every dot splits into a red, a green and a blue stripe, each of which can be dimmed independently of the others.
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Step 3 of 5
Three brightnesses make any colour.
Red and green together read as yellow; all three at full strength read as white. Your eye cannot separate them, so it reports the mixture.
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Step 4 of 5
Movement is just very fast redrawing.
Nothing on the screen ever travels. The whole grid is given a fresh set of colours dozens of times a second, and your brain fills in the motion.
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Step 5 of 5
Enough dots and you stop seeing them.
Dots only look like dots while your eye can still resolve them. Pack them tightly enough and the grid disappears into a smooth image.
A modern phone packs over 400 pixels per inch, while the eye resolves only about 300 at normal reading distance — so the dots vanish.
The short version
Screens show pictures as a grid of dots, each mixing red, green and blue, refreshed fast enough that your eye reads smooth motion.
Try it yourself
Put a drop of water on a phone screen. It acts as a lens, and the separate red, green and blue stripes appear inside each dot.
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