nano-banana

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.

Install

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.

As a Claude Code Skill

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.

Fallback (if bun link doesn't work)

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

Usage

# 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

Models

# 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

Alias	Model	Best For
flash, nb2	Gemini 3.1 Flash Image Preview	Speed, cost, high-volume
pro, nb-pro	Gemini 3 Pro Image Preview	Highest quality, complex composition

Aspect Ratios

# 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

Reference Images

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

Transparent Assets

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

Exact Dimensions

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

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, 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 from generation history
-h, --help	-	Show help

Sizes and Costs