Image generation (diffusion) explained simply

What is it?

Image generators create new pictures from a written description, called a prompt. Many of them use a method called diffusion: the model starts from random noise and removes it step by step until an image that matches the text appears.

The model learned this by training on very large collections of images paired with captions. It does not copy one picture; it combines patterns it has learned about shapes, styles, light and objects. Most tools also let you edit part of an image, extend it, or start from a photo you upload.

Which models use it?

Stable Diffusion is an open family of diffusion models that people can run and customise themselves.
Midjourney is a widely used image generation service.
DALL·E models from OpenAI create images from text, including inside ChatGPT.
Imagen models from Google power image generation in Google products.
Adobe Firefly models are built into Adobe's creative tools.

How to use it

Decide the subject, the setting and the purpose (poster, illustration, product mockup).
Describe the style: photo, watercolour, flat illustration, 3D render, and the mood or colours.
Add composition details such as camera angle, framing, background and aspect ratio.
Generate a few versions, pick the closest one, and refine the prompt one change at a time.
Use editing tools (inpainting, outpainting, variations) to fix specific parts instead of starting over.
Check the result for errors such as extra fingers, broken text or odd objects before using it.

Benefits

Fast visual drafts and concepts without drawing skills.
Easy to explore many styles and ideas in minutes.
Useful for mockups, social posts, storyboards and presentations.
Lets small teams produce visuals that once needed a larger budget.

Limits and risks

Text inside images, hands and exact counts can still come out wrong.
Results can reflect biases from the training data.
Copyright and usage rules differ by tool and country; check the terms before commercial use.
Realistic fake images of real people can mislead or harm; many tools forbid them, and you should not create them.
Getting a very specific result can take many attempts.

Prompt template

Copy it, replace the parts in [brackets] and paste it into any AI chat.

Create an image of [main subject] in [setting or background].
Style: [photo / flat illustration / watercolour / 3D render], mood: [calm / energetic / dramatic], main colours: [colours].
Composition: [close-up / wide shot], [camera angle], subject placed [centre / left third].
Format: [square / portrait / landscape] for [where it will be used].
Avoid: [things you do not want, e.g. text, logos, extra people].

Image generation (diffusion)