Nano Banana 2 Skill

AI image generation CLI powered by Gemini 3.1 Flash Image Preview (default) with support for Gemini 3 Pro and any Gemini model. Multi-resolution (512-4K), aspect ratios, cost tracking, broadcast-grade green screen transparency, reference images, and style transfer.

Also ships as a Claude Code skill for AI-assisted image generation workflows.

Requirements: Bun, FFmpeg + ImageMagick (for transparent mode)

# Clone the repo
git clone https://github.com/kingbootoshi/nano-banana-2-skill.git ~/tools/nano-banana-2
cd ~/tools/nano-banana-2

# Install dependencies
bun install

# Link globally (no sudo needed - uses Bun's global bin)
bun link

# Set up your API key
mkdir -p ~/.nano-banana
echo "GEMINI_API_KEY=your_key_here" > ~/.nano-banana/.env

Get a Gemini API key at Google AI Studio.

Now you can use nano-banana from anywhere.

When installed as a Claude Code skill, just say /init and Claude will clone the repo, install deps, and link the command for you. Then use it by saying "generate an image of..." and Claude handles the rest.

mkdir -p ~/.local/bin
ln -sf ~/tools/nano-banana-2/src/cli.ts ~/.local/bin/nano-banana
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc

# Basic - generates 1K image to current directory
nano-banana "minimal dashboard UI with dark theme"

# Custom output name
nano-banana "luxury product mockup" -o product

# Higher resolution
nano-banana "detailed landscape painting" -s 2K

# Ultra high res
nano-banana "cinematic widescreen scene" -s 4K -a 16:9

# Lower resolution (fast, cheap)
nano-banana "quick sketch concept" -s 512

# Custom output directory
nano-banana "UI screenshot" -o dashboard -d ~/Pictures

# Default - Nano Banana 2 (Gemini 3.1 Flash, fast and cheap)
nano-banana "your prompt"

# Pro - highest quality, 2x cost
nano-banana "your prompt" --model pro

# Any model ID
nano-banana "your prompt" --model gemini-2.5-flash-image

# Widescreen
nano-banana "cinematic landscape" -a 16:9

# Portrait
nano-banana "mobile app screenshot" -a 9:16

# Ultra-wide
nano-banana "panoramic scene" -a 21:9

# Standard photo
nano-banana "product photo" -a 4:3

Supported: 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3, 4:5, 5:4, 21:9

Edit, transform, or combine existing images:

# Edit an 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 UI styles into one" -r style1.png -r style2.png -o combined

# Color correction
nano-banana "make this image more vibrant and increase contrast" -r photo.jpg

Generate assets with transparent backgrounds using AI-powered background removal:

# Basic transparent asset
nano-banana "robot mascot character" -t -o mascot

# Logo with transparency
nano-banana "minimalist tech logo" -t -o logo

# Game asset
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. ImageMagick trims the result. Requires: brew install ffmpeg imagemagick

Control output dimensions by using a blank image as the last reference:

# First -r: your style reference
# Last -r: blank image in target dimensions
nano-banana "pixel art character, 256x256" -r style.png -r blank-256x256.png -o sprite

Every generation logs its cost to ~/.nano-banana/costs.json. View your spending:

nano-banana --costs

Shows total generations, total spend, and per-model breakdown.

The CLI resolves the Gemini API key in priority order:

1. --api-key flag on the command line
2. GEMINI_API_KEY environment variable
3. .env file in the current working directory
4. .env file in the repo root (next to src/)
5. ~/.nano-banana/.env

Get a free key at Google AI Studio.

# Option 1: Environment variable
export GEMINI_API_KEY=your_key_here

# Option 2: .env file in current directory
echo "GEMINI_API_KEY=your_key_here" > .env

# Option 3: Global config
mkdir -p ~/.nano-banana
echo "GEMINI_API_KEY=your_key_here" > ~/.nano-banana/.env

# Option 4: Pass directly
nano-banana "your prompt" --api-key your_key_here

The -t flag uses a 3-step pipeline for pixel-perfect transparency:

1. Green screen prompt - The CLI automatically appends green screen instructions to your prompt, so the AI generates on a solid green background
2. FFmpeg colorkey + despill - colorkey removes the green background. despill reconstructs edge pixel colors by mathematically removing green contamination from the RGB channels - this is why edges are clean instead of having green fringe
3. Auto-crop - ImageMagick trims transparent padding and resets canvas

The key color is auto-detected from corner pixels (the AI generates near-green like #05F904, not exact #00FF00). Requires FFmpeg and ImageMagick: brew install ffmpeg imagemagick

• Landing page assets - product mockups, UI previews
• Image editing - transform existing images with text prompts
• Style transfer - combine multiple reference images
• Marketing materials - hero images, feature illustrations
• UI iterations - quickly generate design variations
• Transparent assets - icons, logos, mascots with no background
• Game assets - sprites, tilesets, characters
• Video production - visual elements for Remotion/video compositions

When installed as a Claude Code plugin, the skill triggers on phrases like:

• "generate an image"
• "create a sprite"
• "make an asset"
• "generate artwork"

Claude will construct the appropriate nano-banana command based on your request, handling model selection, resolution, aspect ratio, reference images, transparency, and output configuration automatically.

MIT