๐ผ๏ธ How does AI generate images?
It learns to remove noise โ and in reverse, that paints a picture from a prompt.
3 min read
Image AI works by learning to destroy and rebuild images. First, the model is trained to add noise to a picture until it's pure static, then reverse the process โ to take static and turn it back into the picture. It learns what makes a 'cat' a cat by repeatedly rebuilding cats from noise.
Once it can turn noise back into images, you can steer it. Give it a text prompt ('a cat astronaut'), and it starts from static and rebuilds โ but this time the rebuild is pulled toward whatever the prompt describes. The text guides the noise-removal toward a cat astronaut instead of just any cat.
That's why image AI is often called 'diffusion': the image 'diffuses' into noise and back, and your prompt nudges the direction. Each generation starts from random static, which is why you get a different image every time โ and why the same prompt never gives the same result twice.
The result is genuinely new images that never existed, built from patterns the model learned. It's remarkable โ and it's why AI images can also get details wrong (hands, text, fingers), because it's predicting what *looks* right, not what *is* right.
๐ Try it in 60 seconds
- 1Use any free image generator and type: 'a lighthouse at sunset, watercolour style'.
- 2Generate the same prompt twice and notice the images differ.
- 3Then ask an AI chat: 'Why do AI images often get hands and text wrong?'
Want the full picture?
Get the free 5-day "AI in your job" email course โ jargon-free, five minutes a day.