nano-banana
AI image generation CLI. Default model: Gemini 3.1 Flash Image Preview (Nano Banana 2).
/init - First-Time Setup
When the user says "init", "setup nano-banana", or "install nano-banana", run these commands to get the CLI tool on their machine. No sudo required.
Prerequisites: Bun must be installed. If not: curl -fsSL https://bun.sh/install | bash
1. Clone the repo
git clone https://github.com/kingbootoshi/nano-banana-2-skill.git ~/tools/nano-banana-2
2. Install dependencies
cd ~/tools/nano-banana-2 && bun install
3. Link globally (creates nano-banana command via Bun - no sudo)
cd ~/tools/nano-banana-2 && bun link
4. Set up API key
mkdir -p ~/.nano-banana echo "GEMINI_API_KEY=<ask user for their key>" > ~/.nano-banana/.env
After init, the user can type nano-banana "prompt" from anywhere.
If bun link fails or the command is not found after linking, fall back to:
mkdir -p ~/.local/bin ln -sf ~/tools/nano-banana-2/src/cli.ts ~/.local/bin/nano-banana
Then ensure ~/.local/bin is on PATH:
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.zshrc source ~/.zshrc
Get a Gemini API key at: https://aistudio.google.com/apikey
Quick Reference
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Command: nano-banana "prompt" [options]
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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
Generate on green screen, remove background (FFmpeg)
--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 needed (~$0.134/1K image)
Sizes
Size Cost (Flash) Cost (Pro)
512
~$0.045 Flash only
1K
~$0.067 ~$0.134
2K
~$0.101 ~$0.201
4K
~$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
Use -a flag: nano-banana "cinematic scene" -a 16:9
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
Model Selection
Default (Flash - fast, cheap)
nano-banana "your prompt"
Pro (highest quality)
nano-banana "detailed portrait" --model pro -s 2K
Reference Images (Style Transfer / Editing)
Edit existing image
nano-banana "change the background to pure white" -r dark-ui.png -o light-ui
Style transfer - multiple references
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 automatically prompts the AI to generate on a green screen, then uses FFmpeg colorkey
- despill to key out the background and remove green spill from edge pixels. Pixel-perfect transparency with no manual prompting needed.
Requires: brew install ffmpeg imagemagick
Exact Dimensions
To get a specific output dimension:
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First -r flag: your reference/style image
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Last -r flag: blank image in target dimensions
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Include dimensions in prompt
nano-banana "pixel art character in style of first image, 256x256" -r style.png -r blank-256x256.png -o sprite
Reference Order Matters
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First reference: primary style/content source
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Additional references: secondary influences
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Last reference: controls output dimensions (if using blank image trick)
Cost Tracking
Every generation is logged to ~/.nano-banana/costs.json . View summary:
nano-banana --costs
Use Cases
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Landing page assets - product mockups, UI previews
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Image editing - transform existing images with prompts
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Style transfer - combine multiple reference images
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Marketing materials - hero images, feature illustrations
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UI iterations - quickly generate variations of designs
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Transparent assets - icons, logos, mascots with no background
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Game assets - sprites, backgrounds, characters
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Video production - visual elements for video compositions
Prompt Examples
UI mockups
nano-banana "clean SaaS dashboard with analytics charts, white background"
Widescreen cinematic
nano-banana "cyberpunk cityscape at sunset" -a 16:9 -s 2K
Product shots with Pro quality
nano-banana "premium software product hero image" --model pro
Quick low-res concept
nano-banana "rough sketch of a robot" -s 512
Dark mode UI
nano-banana "Premium SaaS chat interface, dark mode, minimal, Linear-style aesthetic"
Game assets with transparency (green screen auto-prompted)
nano-banana "pixel art treasure chest" -t -o chest
Portrait aspect ratio
nano-banana "mobile app onboarding screen" -a 9:16
API Key Setup
The CLI resolves the Gemini API key in this order:
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--api-key flag
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GEMINI_API_KEY environment variable
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.env file in current directory
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.env file next to the CLI script
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~/.nano-banana/.env
Get a key at: https://aistudio.google.com/apikey