# Writing prompts that produce usable images

Lesson 1 of [Choosing and using AI image tools](https://aiimagegen.fyi/academy/choose-and-use-ai-image-tools.md), 20 minutes.

A good image prompt reads like a brief to a photographer, not a list of keywords. Two vendor prompt guides agree on the shape, and both were read on 2026-11-13.

## The basic structure

Black Forest Labs' prompt guide suggests this order as a habit, not a rule: image type and medium, subject, setting, light, then framing and detail. OpenAI's prompting guide gives parallel advice: start with the image you need, describe the subject, composition, style and constraints, and for edits say what should change and what must stay the same.

A worked example for a product shot:

```text
Editorial product photograph, soft diffused daylight from the left.
Warm off-white seamless background, shallow depth of field.
A matte terracotta ceramic mug, no logo, handle on the right, centered.
Keep the mug shape and glaze identical to the reference image.
No text, no props, no watermark.
```

Each sentence does a job: medium, light, background, subject, constraint, exclusion.

## Practical habits

1. Start with a sentence and add detail as you review results. BFL's guide notes a longer prompt helps for several subjects, a specific layout or text in the image, and that quality tags such as "masterpiece" can be omitted.
2. For photorealistic goals, request "photorealistic" or "real photograph" explicitly and describe framing and texture; OpenAI's guide notes camera terms are cues, not guarantees of exact simulation.
3. Quote exact text when the image must contain words, and say how many times it should appear.
4. Refine one thing at a time. Pass the previous output as the next edit input, request one change, and restate the constraints that must hold. OpenAI's guide warns that phrases like "same style as before" can carry context but critical constraints should be restated if the result drifts.
5. Describe negatives as positives where the tool prefers it; BFL's technical prompting page recommends positive descriptions over negative prompts.

## Iterate deliberately

Most workflows need two to four attempts per keeper. Budget for it in cost and time. When the image drifts, the fix is usually fewer changes per step and more restated constraints, not a longer prompt.

## Sources

- [OpenAI image prompting guide](https://platform.openai.com/docs/guides/image-prompting), accessed 2026-11-13.
- [OpenAI image generation guide](https://platform.openai.com/docs/guides/image-generation), accessed 2026-11-13.
- [Black Forest Labs, Building a Good Prompt](https://docs.bfl.ml/guides/prompting_unified_building.md), accessed 2026-11-13.
- [Black Forest Labs, Prompting Basics](https://docs.bfl.ml/guides/prompting_unified_basics.md), accessed 2026-11-13.

Also on the [web page](https://aiimagegen.fyi/academy/choose-and-use-ai-image-tools/writing-prompts-that-work).