| name | nano-banana |
| description | Generates AI images using the nano-banana CLI (Gemini 3.1 Flash default, Pro available). Handles multi-resolution (512-4K), aspect ratios, reference images for style transfer, green screen workflow for transparent assets, cost tracking, and exact dimension control. Use when asked to "generate an image", "create a sprite", "make an asset", "generate artwork", or any image generation task for UI mockups, game assets, videos, or marketing materials. |
nano-banana
When to use
- Generating AI images for UI mockups, game sprites, marketing assets, or video content via the
nano-banana CLI.
- Any task asking to "generate an image", "create a sprite", "make an asset", or produce artwork at specific resolutions.
- Style-transfer from a reference image, green-screen transparent assets, or multi-resolution output (512–4K).
AI image generation CLI. Default model: Gemini 3.1 Flash Image Preview (Nano Banana 2).
Installed at: ~/tools/nano-banana-2/
Binary: ~/.bun/bin/nano-banana
Prerequisites
- Bun (installed at
~/.bun/bin/bun)
- FFmpeg + ImageMagick for transparent mode:
brew install ffmpeg imagemagick
- Gemini API key at
~/.nano-banana/.env (get at https://aistudio.google.com/apikey)
Quick Reference
- Command:
nano-banana "prompt" [options]
- Default: 1K resolution, Flash model, current directory
Core Options
| Option | Default | Description |
|---|
-o, --output | nano-gen-{timestamp} | Output filename (no extension) |
-s, --size | 1K | Image size: 512, 1K, 2K, or 4K |
-a, --aspect | model default | Aspect ratio: 1:1, 16:9, 9:16, 4:3, 3:4, etc. |
-m, --model | flash | Model: flash/nb2, pro/nb-pro, or any model ID |
-d, --dir | current directory | Output directory |
-r, --ref | - | Reference image (can use multiple times) |
-t, --transparent | - | Green screen + FFmpeg background removal |
--api-key | - | Gemini API key (overrides env/file) |
--costs | - | Show cost summary |
Models
| Alias | Model | Use When |
|---|
flash, nb2 | Gemini 3.1 Flash | Default. Fast, cheap (~$0.067/1K image) |
pro, nb-pro | Gemini 3 Pro | Highest quality (~$0.134/1K image) |
Sizes & Costs
| Size | Resolution | Flash Cost | Pro Cost |
|---|
512 | ~512x512 | ~$0.045 | Flash only |
1K | ~1024x1024 | ~$0.067 | ~$0.134 |
2K | ~2048x2048 | ~$0.101 | ~$0.201 |
4K | ~4096x4096 | ~$0.151 | ~$0.302 |
Aspect Ratios
Supported: 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3, 4:5, 5:4, 21:9
Key Workflows
Basic Generation
nano-banana "minimal dashboard UI with dark theme"
nano-banana "cinematic landscape" -s 2K -a 16:9
nano-banana "quick concept sketch" -s 512
Pro Model (highest quality)
nano-banana "detailed portrait" --model pro -s 2K
Reference Images (Style Transfer / Editing)
nano-banana "change the background to pure white" -r dark-ui.png -o light-ui
nano-banana "combine these two styles" -r style1.png -r style2.png -o combined
Transparent Assets
nano-banana "robot mascot character" -t -o mascot
nano-banana "pixel art treasure chest" -t -o chest
The -t flag: green screen prompt -> FFmpeg colorkey + despill -> ImageMagick trim.
Exact Dimensions
nano-banana "pixel art character, 256x256" -r style.png -r blank-256x256.png -o sprite
Prompting Best Practices
- Natural language — write sentences, not keyword lists
- Be specific — include subject details, materials, lighting, mood
- Include context — what is the image for (landing page, game asset, etc.)
- Edit conversationally — refine existing generations with
-r flag
Anti-Patterns (avoid)
- Tag-soup keywords:
beautiful, HD, 4K, masterpiece
- Vague subjects:
a nice landscape
- Missing mood/lighting: just describing objects without atmosphere
- Over-prompting: contradictory instructions
Good Prompt Examples
nano-banana "clean SaaS dashboard with analytics charts, white background"
nano-banana "cyberpunk cityscape at sunset, neon reflections on wet streets" -a 16:9 -s 2K
nano-banana "premium software product hero image, floating UI elements" --model pro
nano-banana "pixel art treasure chest, wooden with gold trim" -t -o chest
nano-banana "Premium SaaS chat interface, dark mode, minimal, Linear-style aesthetic"
Use Cases
- Landing page assets (product mockups, hero images)
- Image editing (transform with text prompts +
-r)
- Style transfer (combine multiple references)
- Marketing materials (feature illustrations)
- UI iterations (quick design variations)
- Transparent assets (icons, logos, mascots with
-t)
- Game assets (sprites, characters, tilesets)
- Video production (visual elements for compositions)
- 3D website animations (generate keyframes for scroll-driven animations)
Cost Tracking
Every generation logged to ~/.nano-banana/costs.json.
nano-banana --costs
API Key Resolution Order
--api-key flagGEMINI_API_KEY env var.env in current directory.env in repo root~/.nano-banana/.env
