The first time I used the full reference allowance, the image got worse.

Fourteen images: the character, two angles of her face, the jacket, the studio, the palette, a texture, a light reference, three mood boards. What came back was a competently lit photograph of nobody in particular. The model had done what a model does with fourteen inputs: it found the average.

That is the thing to understand about reference budgets. The number is a ceiling, not a target, and every image you attach past the useful set is a competing instruction.

I ran into this on Callirra, which exposes fourteen slots and no opinion about how to use them.

What the model actually accepts

Limit	Value
References per run	14
Character references documented by Google	4
High-fidelity object references documented by Google	10
Prompt length	20,000 characters
Output resolutions	1K, 2K, 4K
Credits per image	3 / 4 / 5

The 4 + 10 split is the most useful number on that table, because it tells you what the allowance is for: up to four people and up to ten objects, not fourteen of anything.

The four roles, not fourteen images

A reference set is a cast list. Each image has one job, and if two images have the same job, one of them is noise:

Identity — the face or the product. One clean, evenly lit, front-on image. This one is non-negotiable.
Structure — the angle or the pose you intend to render. Two or three quarters of the same subject, from the same reference shoot if possible.
Material — the thing that has to look right at 100%: fabric, glass, condensation, powder, skin texture.
World — palette, light direction, background. This is the reference people over-spend on, and it is the one that survives best as a written sentence instead of an image.

Four images cover all four roles for a single character. Ten covers a product range. Fourteen is for a scene with four characters and several objects — which is exactly the case the 4 + 10 split describes.

Spend the budget like this

Shot	Identity	Structure	Material	World	Total
Portrait with a wardrobe change	1	2	1	0	4
Product hero on a set	1 object	1 angle	1	0	3
Line-up of four characters	4	4	2	1	11
Editorial still life, two products	2 objects	1	2	1	6

Note what is missing from every row: mood boards. A mood board is a description of taste, and taste is cheaper to write than to reference.

Say what each reference owns

The prompt does not have to describe the images — that is the reference's job. It has to say which image owns which decision:

Use the supplied images as follows:
- image 1 owns identity: face, hair, skin tone. Do not change her features.
- image 2 owns the jacket: cobalt wool, exact cut.
- image 3 owns the light: single soft key from camera left, deep shadow right.
- image 4 owns the palette only.

Render her in a sunlit gallery, three-quarter view, same identity and jacket.

Compare that with "use the references", which is what produces the average. The moment a reference has an owner and a scope, conflicting inputs stop being a vote and start being a spec.

Where it goes wrong

Two references that disagree. Two jacket photos in different blues means the model picks a third blue. Pick one and delete the other.

References that fight the prompt. "Preserve the exact shape and colour" alongside three shape variants is a request to reconcile the irreconcilable.

Assuming PNG means transparency. It does not on this model: choosing PNG does not guarantee a transparent background, and there are no background or quality controls here at all — aspect ratio, resolution, JPG/PNG and references are the whole surface.

Treating 14 as headroom to use "just in case". Every unused reference is a liability: it is one more thing the model must decide the weight of.

The iteration trick that beats a bigger reference set

Reuse the output as the next reference. The model keeps identity better across a chain of edits than across a pile of inputs, and the chain is auditable: each step has one changed instruction.

Render the base frame with four references.
Feed that frame back, change the background, keep identity locked in the prompt.
Feed the result back for the wardrobe change.

Three steps, three credits each at 1K, and a character who stays the same person — which is what people actually mean when they ask for "consistency".

FAQ

Does more references cost more credits? No. The price is per resolution: 3 / 4 / 5 for 1K / 2K / 4K.

Can I mix characters and objects freely? Within the documented split — up to four characters and up to ten objects.

Is a reference image required? No, text-to-image works. References are what you add when identity or material has to hold.

What if the text on a product must be exact? This model is strong at text, but review it at 100% anyway; small type is where every model still slips.

The reference limits and the 4 + 10 split are documented on Callirra's Nano Banana 2.1 page. If you have a fourteen-reference workflow that consistently beats a four-reference one, I want to see the prompt — that would break the pattern above.

StackFeed

Nano Banana 2.1: fourteen references, four that matter