Nano Banana

Verified against Nano Banana / Gemini 3.1 Flash Image · 2026-07-28

Preview a sign or logo design on an actual storefront

Mounts a flat sign or logo design onto a photo of a real storefront at the correct scale, material, and mounting position — the check a business owner needs before committing to fabrication and installation.

Nano Banana (Gemini 3.1 Flash Image)Gemini app5 fillable variables

The prompt

Ready to copy — highlighted parts are example details you can swap.

You are creating a mockup showing how a sign or logo design would look actually installed on a real storefront, before it's fabricated. The design and the storefront photo are both fixed inputs — your job is to composite them believably, not to redesign either one.

SIGN OR LOGO DESIGN
a wordmark logo in brushed-gold dimensional letters reading "MERIDIAN COFFEE", uploaded as a flat design file.

STOREFRONT PHOTO
a narrow brick storefront with a single large window and a plain fascia board above the entrance, shot straight-on from across the street. Preserve the storefront's actual architecture, materials, and existing lighting conditions exactly as photographed.

MOUNTING LOCATION AND SCALE
centered on the fascia board above the entrance, sized to fill roughly two-thirds of the fascia's width with even margin on both sides. Use the storefront's actual visible architectural features — the width of the doorway, the height of the window band, the depth of the fascia board — as real scale references so the sign renders at a size that would actually be fabricable and legally plausible for that specific mounting surface, not an arbitrarily large or small rendering that ignores the real dimensions available.

MATERIAL AND LIGHTING EFFECT
brushed-metal dimensional letters, non-illuminated, should show a soft metallic highlight from the sun and a subtle cast shadow onto the fascia. Render the sign's actual material properties given the time of day specified below — an illuminated channel-letter sign should show genuine glow and a soft light spill onto the surrounding facade if this is a dusk or night scene, a painted or vinyl sign should show flat, non-illuminated color reading naturally under ambient daylight, and a dimensional metal sign should pick up real specular highlights and cast a subtle shadow onto the wall behind it consistent with the sun's position in the reference photo.

TIME OF DAY
mid-afternoon daylight, sun coming from the upper right based on the shadows already visible in the storefront photo. This changes more than the sign's own lighting — it determines the ambient light on the whole storefront, so keep the rest of the building's existing lighting consistent with whatever time of day is specified, not mismatched to a different lighting scenario than the sign itself.

PERSPECTIVE MATCHING
The sign must sit on the mounting surface at the exact same perspective and vanishing-point angle as the storefront photo was shot from — if the photo was taken at a slight angle rather than dead-on, the sign's letters and edges need to show that same angle's foreshortening, not render as if seen perfectly straight-on while everything else in the photo is angled.

WHAT NOT TO CHANGE
Do not alter the storefront's existing architecture, other signage, window displays, or the street scene around it — this mockup is testing one new sign against a real, unmodified location, not proposing a full storefront redesign.

OUTPUT
One mockup image showing the proposed sign mounted realistically in place, at fabricable scale, under the specified lighting conditions — suitable for a client-approval conversation or an initial landlord/permit discussion before fabrication is ordered.

Customize

Optional — swap in your own details for the highlighted parts above.

Why this works

Grounding the sign's scale in the storefront's own visible architectural measurements — doorway width, fascia depth — rather than an arbitrary visually-balanced size matters because this specific mockup has a real downstream consequence a purely aesthetic mockup doesn't: a business owner or landlord is going to make a fabrication and, often, a permitting decision partly based on how this image looks, and a sign rendered at a size that couldn't actually be fabricated to fit the real fascia board creates expectations the physical installation can't meet, turning a helpful visualization into a source of an expensive surprise later. Second, tying the sign's lighting effect to the specified time of day, and requiring the rest of the storefront's ambient lighting to stay consistent with that same time of day, targets a subtle inconsistency that's easy to introduce when compositing a new element into an existing photo: a sign rendered with a confident dusk-time illuminated glow, mounted onto a storefront photo whose windows and shadows clearly show midday sun, reads as visually contradictory the moment someone looks closely, even if neither element is wrong in isolation. Third, the perspective-matching requirement addresses a specific compositing error that's common precisely because it's easy to overlook: a sign added to a photo shot at a slight angle needs to share that same angle's foreshortening on its own letters and edges, and a flat, straight-on rendering of the sign pasted onto an angled photo produces a mockup where the new sign looks like a sticker applied after the fact rather than an object that was actually mounted on the building when the photo was taken — which undermines the entire credibility of the mockup as a preview of a real installation rather than a rough concept sketch.

Verified against

Nano Banana / Gemini 3.1 Flash Image Gemini 3.1 Flash Image · 2026-07-28

Changelog

  • 2026-07-28 Initial publish, verified against Nano Banana (Gemini 3.1 Flash Image) on a brushed-metal fascia sign mockup.

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