Nano Banana Image Generator

Generate high-quality image assets using Google's Gemini image generation API (internally codenamed "Nano Banana"). Supports both OpenRouter and direct Google API.

When to Use

•Creating UI component mockups, icons, or illustrations for projects
•Generating placeholder images or design assets
•Producing marketing visuals or social media graphics
•Creating diagrams or conceptual visualizations

Prerequisites

•Python 3.11+ with httpx (uv add httpx)
•
One of:
- •OpenRouter API key (preferred): export OPENROUTER_API_KEY='your-key'
- •Google API key: export GOOGLE_API_KEY='your-key'

Quick Start

bash

# With OpenRouter (auto-detected if OPENROUTER_API_KEY is set)
python ~/.claude/skills/nano-banana-imagegen/scripts/generate.py "minimalist search icon"

# Explicit provider
python ~/.claude/skills/nano-banana-imagegen/scripts/generate.py "dark mode toggle" --provider openrouter

Workflow

Basic Generation

bash

python ~/.claude/skills/nano-banana-imagegen/scripts/generate.py "your prompt"

With Options

bash

python ~/.claude/skills/nano-banana-imagegen/scripts/generate.py "your prompt" \
  --resolution 2K \
  --style minimalist \
  --output ./my-image.png \
  --count 3 \
  --provider openrouter

Available Options

Option	Values	Default	Description
`--resolution`	1K, 2K, 4K	2K	Output resolution
`--style`	minimalist, realistic, illustration, technical	minimalist	Style preset
`--output`	path	auto	Output file path
`--count`	1-4	1	Number of variations
`--model`	flash, pro, flash-thinking	flash	Model selection
`--provider`	openrouter, google, cli	auto	API provider

Provider Comparison

Provider	Env Variable	Free Tier	Notes
OpenRouter	`OPENROUTER_API_KEY`	Yes (gemini-2.0-flash-exp:free)	Preferred, unified API
Google	`GOOGLE_API_KEY`	Limited	Direct access
CLI	N/A	Varies	Requires gemini CLI

Prompt Engineering Tips

Formula for Quality Results

code

[SUBJECT] [COMPOSITION] [STYLE] [TECHNICAL] [QUALITY]

Examples

UI Component:

code

Modern dark mode toggle switch, glass morphism style,
centered composition, minimalist flat design, 24x24 size,
rounded corners, blue-to-purple gradient, high contrast

Icon Set:

code

Minimalist search magnifying glass icon, thin line weight,
monochrome black on transparent, 24x24 pixels,
clean geometric shapes, suitable for app UI

Marketing Visual:

code

Abstract technology background, flowing data streams,
blue and purple color palette, modern tech aesthetic,
16:9 aspect ratio, suitable for hero section

Configuration

Optional config file: ~/.config/nano-banana/config.json

json

{
  "provider": "openrouter",
  "default_resolution": "2K",
  "default_style": "minimalist",
  "output_directory": "./generated_assets"
}

Rate Limits & Costs

OpenRouter

•Free tier: gemini-2.0-flash-exp:free available
•Pay-per-use for other models
•Check https://openrouter.ai/models for current pricing

Google Direct

•Free tier: ~15 requests/minute
•Pro tier: ~60 requests/minute
•Cost: ~$0.10 per 4K image

Limitations

•Best for design assets, icons, illustrations
•Complex photographs may lack realism
•Text rendering can be inconsistent
•OpenRouter may return text descriptions instead of images for some prompts

Integration with Other Skills

•Pair with repo-reviewer for design asset audits
•Use git-committer after finalizing assets
•Store generated assets in project's assets/ or static/ directory