How animation works: frames, speed and your brain

Every animated film is really a set of still pictures shown very fast. Each picture is called a frame. When frames change quickly and each one is only a little different from the one before, your brain joins them together and you see smooth movement.

Your brain fills the gaps

Your eyes send pictures to your brain, and your brain is always trying to make sense of them. When it sees a ball in one place and then a ball just beside it a moment later, it decides the ball moved. Scientists call this apparent motion. It is the same reason the lights on a sign can seem to run around its edge.

Old toys, same trick

Frame rate

Frame rate is how many frames are shown each second, written as fps (frames per second). Cinema films usually use 24 fps. Many stop-motion films use 12 different pictures a second, each shown twice. This is called animating 'on twos'. At school, 8–12 fps looks good and saves time.

Do the maths

Stop motion

In stop-motion animation, you move a real object a tiny bit, take a photo, and repeat. Clay figures, paper cut-outs, toys, sand and even people can be animated. Apps help with onion skinning, which shows a see-through version of the last frame so you can judge how far to move things.