Nano Banana Image Generator

Generate AI images styled with the Nano Banana Pro visual identity using Google Gemini API.

Key Features

• Nano Banana Pro Style: Auto-applies signature dark navy, golden yellow, teal color palette

• Multi-Key Support: Manage multiple Gemini API keys

• Round-Robin Rotation: Automatically rotates keys to distribute API usage

• Multiple Aspect Ratios: 1:1, 16:9, 9:16, 4:3, 3:4

Quick Start

Generate an image

python scripts/generate_image.py "a futuristic productivity device" output.png

With aspect ratio

python scripts/generate_image.py "app icon with lightning bolt" icon.png --aspect 1:1

API Key Management

Keys are stored in ~/.config/nano-banana-image/config.json and used in round-robin order.

List Keys

python scripts/generate_image.py keys list

Output:

Configured API Keys (2) - Round Robin Mode:

1. default: AIzaSyDu8m...4Z0I [LAST USED]
2. secondary: AIzaSyAxUw...ydqk [NEXT]

Strategy: Round-robin (auto-rotate on each call)

Add a Key

python scripts/generate_image.py keys add <name> <api-key>

Examples:

python scripts/generate_image.py keys add default AIzaSy... python scripts/generate_image.py keys add work AIzaSy...

Remove a Key

python scripts/generate_image.py keys remove <name>

Reset Rotation

python scripts/generate_image.py keys reset

Restarts round-robin from the first key.

First-Time Setup

On first use with no keys configured:

python scripts/generate_image.py --check

This shows setup instructions. User provides key, then:

python scripts/generate_image.py keys add default "AIzaSy..."

Image Generation

Usage

python scripts/generate_image.py "<description>" [output_path] [options]

Argument Description Default

description

What to generate (required)

output_path

Output file path output.png

--aspect

Aspect ratio: 1:1, 16:9, 9:16, 4:3, 3:4 16:9

--model

Gemini model to use gemini-3-pro-image-preview

--key

Use specific key (skips rotation) next in rotation

Use Specific Key

Use 'work' key for this generation only (doesn't affect rotation)

python scripts/generate_image.py "prompt" output.png --key work

Style Applied

All generated images automatically include Nano Banana Pro styling:

• Colors: Deep navy (#1C2833), golden yellow (#F4C430), teal (#00D9C0)

• Mood: Professional, tech-forward, premium, innovative

• Aesthetic: Dark mode, geometric shapes, high contrast, minimalist

Examples

Product Visualization

python scripts/generate_image.py "a compact smart device with glowing edges" product.png

Abstract Background

python scripts/generate_image.py "abstract geometric pattern with flowing particles" bg.png --aspect 16:9

Icon/Logo

python scripts/generate_image.py "minimalist sync icon with two rotating arrows" icon.png --aspect 1:1

Hero Image

python scripts/generate_image.py "futuristic AI brain with neural connections" hero.png

Prompt Tips

For best results, describe:

• Subject: What is the main focus

• Context: Environment or setting

• Mood: Energy level, feeling

• Details: Specific elements to include

The Nano Banana style (colors, aesthetic) is automatically added.

Good prompts:

• "a sleek handheld device floating above a hand, soft glow"

• "abstract data visualization with flowing particles"

• "modern office desk with minimal tech accessories"

Avoid:

• Overly detailed color specifications (style is auto-applied)

• Conflicting aesthetic directions (e.g., "vintage rustic style")

Output

• Format: PNG (or JPG/WebP based on API response)

• Resolution: Determined by Gemini model

• Watermark: SynthID embedded (invisible, for authenticity)

Troubleshooting

Error Solution

No API keys configured

Run keys add <name> <key>

Key 'xxx' not found

Run keys list to see available keys

HTTP 403

Key invalid or lacks permissions

HTTP 429

Rate limited - round-robin helps distribute load

No image generated

Rephrase prompt, avoid restricted content

Security

• Keys stored in ~/.config/nano-banana-image/config.json

• File permissions set to 600 (owner read/write only)

• Keys never logged or displayed in full (masked as AIza...xxxx )

• Fallback to GEMINI_API_KEY environment variable supported

Command Reference

Command Description

keys list

List all keys with rotation status

keys add <name> <key>

Add a new API key

keys remove <name>

Remove an API key

keys reset

Reset rotation to first key

--check

Check configuration status

--key <name>

Use specific key for one generation