Nano Banana Pro - Gemini Image Generation (Windows Compatible)

Generate custom images using Google's Gemini models for integration into frontend designs.

Prerequisites

Windows Setup

1. Install uv - Python package manager:

   # PowerShell (as Admin)
   irm https://astral.sh/uv/install.ps1 | iex
   

2. Set the GEMINI_API_KEY environment variable:

   # Temporary (current session only)
   $env:GEMINI_API_KEY = "your-api-key-here"
   
   # Permanent (User level)
   [Environment]::SetEnvironmentVariable("GEMINI_API_KEY", "your-api-key-here", "User")
   

   Or via Windows Settings:

   • Search "Environment Variables" in Start Menu
   • Click "Edit environment variables for your account"
   • Add new variable: GEMINI_API_KEY with your API key

Available Models

Model	ID	Best For	Max Resolution
Flash	gemini-2.5-flash-image	Speed, high-volume tasks	1024px
Pro	gemini-3-pro-image-preview	Professional quality, complex scenes	Up to 4K

Image Generation Workflow

Step 1: Generate the Image

Use scripts/image.py with uv:

uv run "${SKILL_DIR}/scripts/image.py" \
  --prompt "Your image description" \
  --output "/path/to/output.png"

Windows PowerShell:

uv run "$env:SKILL_DIR\scripts\image.py" `
  --prompt "Your image description" `
  --output "C:\path\to\output.png"

Options:

• --prompt (required): Detailed description of the image to generate
• --output (required): Output file path (PNG format)
• --aspect (optional): Aspect ratio - "square", "landscape", "portrait" (default: square)
• --reference (optional): Path to a reference image for style guidance
• --model (optional): Model to use - "flash" (fast) or "pro" (high-quality) (default: flash)
• --size (optional): Image resolution for pro model - "1K", "2K", "4K" (default: 1K)

Using Different Models

Flash model (default) - Fast generation:

uv run "${SKILL_DIR}/scripts/image.py" \
  --prompt "A minimalist logo design" \
  --output "/path/to/logo.png" \
  --model flash

Pro model - Higher quality:

uv run "${SKILL_DIR}/scripts/image.py" \
  --prompt "A detailed hero illustration" \
  --output "/path/to/hero.png" \
  --model pro \
  --size 2K

Crafting Effective Prompts

Write detailed, specific prompts for best results:

Good prompt:

A minimalist geometric pattern with overlapping translucent circles in coral, teal, and gold on a deep navy background, suitable for a modern fintech landing page hero section

Avoid vague prompts:

A nice background image

Prompt Elements to Include

1. Subject: What the image depicts
2. Style: Artistic style (minimalist, abstract, photorealistic, illustrated)
3. Colors: Specific color palette
4. Mood: Atmosphere (professional, playful, elegant, bold)
5. Context: How it will be used (hero image, icon, texture)