How to write brand rules an AI can follow
Write rules as things a camera can do: colors as a name plus hex code, where the light comes from and how soft it is, the lens and distance, the surfaces, the casting and the props allowed. Replace words like "premium" or "modern" with the visual facts behind them. Keep it to one page and apply it last, after the brief and the visual DNA, so the rules win any conflict.
What goes in a brand rules document
Twelve short parts cover most brands. Every line should be something a reviewer can check by looking at the image. Copy the template, fill the blanks, and cut any line you cannot check.
BRAND RULES FOR AI IMAGES Brand: ________ Version and date: ________ Owner: ________ 1. WHO WE ARE (one sentence) What we sell, to whom, and the one feeling our pictures should leave. 2. OUR CUSTOMER Age range, where they live, what their home and day look like. Props and places come from here. 3. VOICE WORDS, AS VISIBLE FACTS (three at most) "________" means ________ in a photo. Example: "Honest" means real skin texture, true product scale, no retouched pores. 4. PALETTE (name, hex, role, most of the frame it may fill) - ________ #______ grounds and walls, up to __% - ________ #______ product or one accent, up to __% - ________ #______ shadows and type only 5. LIGHT Direction (camera left, right, behind, above), soft or hard, neutral, warm or cool, time of day. 6. LENS AND DISTANCE Wide, standard or long-lens look. Camera height. How close. 7. COMPOSITION Where the product sits. How much empty space, and where copy will go. 8. GROUNDS AND SURFACES Backgrounds and materials allowed, with hex codes. 9. STYLING AND PROPS Allowed: ________. At most __ props per frame. Banned: ________. 10. CASTING (if people appear) Ages, looks, poses, where they look, hands and nails. 11. FINISH Grain, contrast, how deep the blacks go, what retouching is allowed. 12. NEVER DO (six to twelve lines a reviewer can see) - ________ WORDS ON IMAGES: never in the render / set later in a design tool. Typeface: ________ IF ANYTHING IN THE BRIEF CONFLICTS WITH THESE RULES, THESE RULES WIN.
Part 12 has its own guide and template: how to write a never-do list for AI images. If your brand already has a guidelines PDF, start from that: turning brand guidelines into AI rules.
Why the brand rules go last
In our agency’s workflows, three documents feed the prompts in a fixed order. The brief says what this campaign needs. The brand bible says who the brand is. The visual DNA says how its pictures look. The brand rules come after all three, so when the brief asks for something the brand does not do, the rules have the final word.
OpenAI’s guide for GPT Image 2.5 recommends a similar shape for complex prompts: scene, subject, details, then constraints, in labeled sections. Put the brand rules in the constraints position and say in plain words that they win.
How long should the rules be?
One page. Long enough to cover the twelve parts, short enough that a reviewer can check an image against it in a minute. The rules document is the source, and each prompt carries only the lines its shot needs, written as what you want to see. The full never-do list stays with the reviewer, because a prompt that lists what to avoid still names those things.
Prompts have their own length. In our agency’s 2026 campaigns, the prompts behind kept photos ran about 140 to 200 words on Nano Banana models and about 300 words on GPT Image. The order inside a prompt is covered in how to write an AI image prompt for a product.
Test the rules before a campaign
- Pick three shots you make often, such as a packshot, a lifestyle scene and a close-up.
- Render each one five times with the rules and the same reference photos.
- Score all fifteen with the on-brand scorecard.
- Find the lines that failed more than once, and rewrite each one so it names something visible.
- Change one rule at a time and render again. OpenAI’s guide gives the same advice for prompts: refine one thing at a time and inspect the result.
- Keep the version that scores better, and date it.
Questions people also ask
- Should hex codes go in the prompt?
- Yes, next to a color name, such as "terracotta #B5562F". Google’s and OpenAI’s image prompting guides do not mention hex codes, so treat the hex as a hint and the name as the instruction. A reference photo that shows the color does more; see keeping brand colors accurate.
- Can one rules document work across image models?
- Yes. Keep one rules document and build a prompt template for each model from it. Models differ in how much text they handle well and in the structure their makers recommend, so the same rule may need different wording on Nano Banana and on GPT Image. Test each template on the same three shots.
- Who should write the rules?
- The person who approves images, usually the brand manager, with the photographer or creative director writing the light and lens lines. If nobody can say where your light comes from, measure it from 10 to 20 of your best images. That measurement is your visual DNA.
Where Overs fits
Overs writes brand rules from your website, your existing photos and an optional brand guidelines PDF of up to 24 pages, as one of ten steps you can watch. The rules are applied last, so they have the final say.
Free for 40 photos a month. The AI that makes the photos is billed separately, on your own key, with no markup from Overs.