The four locks behind a consistent AI picture book

“Make the same character on every page” sounds like one feature. It’s really four, because a generative image model has no memory between requests, so every page is an independent guess. Getting a recognisable child across every page means removing the guessing at four separate points. Below is each lock, and what breaks without it.

1. Canonicalise the character into structured descriptors

A prompt like “a curly-haired girl” leaves a thousand degrees of freedom. We pin them down into a Character Sheet: explicit, immutable fields for hair, eyes, build, outfit and distinguishing features. It’s structured rather than prose, so the same values feed every generation identically. Without it, you’re back to reinventing the character from loose words each time.

2. Condition on approved reference images

Words alone can’t carry a face. We render the character once into an Identity Sheet, the same child in canonical poses, and supply those reference images to condition every later page. The model draws from the reference, not from its own last output. Without it, likeness drifts even when the description is fixed.

3. Freeze the style and control the seed

Two more sources of variance: the art direction and the random seed. We freeze a Style Profile onto the whole book at creation, so page one and page twelve share a medium, palette and lighting. We also send and keep a seed with each page, so a regeneration is a deliberate variation rather than a fresh random guess. The seed is the weaker of the two, and worth being straight about: the image model we render on exposes no true seed field, so a seed nudges a result rather than reproducing it exactly. The frozen style is what actually holds the look together. Without it you get a different illustrator every few pages, the clearest tell of drift.

4. Keep a human approval gate

No classifier is perfect, so the last lock is you. Nothing enters the book until you’ve approved it, and any page can be regenerated on its own. Drift that slips past the first three locks is caught here, before it reaches print.

Together these are what we call the Consistency Engine. Miss any one and the book reads as AI slop; hold all four and it reads as one book. See the four-step flow, or flip through a finished sample to watch the character hold.