Pixels make digital pictures — Computing, 11–13 years
How a screen builds a picture from tiny coloured points. Computing, 11–13 years.
A picture is a grid
Zoom in far enough on a digital picture and it becomes a grid of tiny squares called pixels. Each pixel stores a colour, and all the pixels together create the picture your eyes recognise. More pixels can show finer detail, but the image also needs more space to store.
Why break pictures into pixels?
A screen needs a precise instruction for every small part it can light up. A grid gives each part a position and a colour, so the computer can draw, save and change a picture in a reliable way. This solved the problem of turning continuous-looking photographs and drawings into information that electronic devices could handle.
A tiny three-colour image
Imagine a 3 by 2 image: six pixels in two rows. The top row is red, red, white; the bottom row is red, blue, red. The computer stores the grid and each colour, then lights the six positions. From a distance it looks like a tiny pattern, but up close you can see its separate squares.
Zooming does not add detail
People often expect a blurry image to become sharp when enlarged, because a bigger view feels as if it should reveal more. Enlargement can spread existing pixels over more screen space, but it cannot recover details that were never recorded. A sharper version needs better original data, not just a larger display.
Photos, games and maps
Phone photos, game characters, weather maps and medical scans all use grids of coloured or shaded pixels. Editing software changes selected pixels to crop a picture, remove a mark or alter its colours. Pixel size matters too: a tiny icon can look clear, while a large poster needs many more pixels to avoid looking blocky.
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