Nano Banana - AI Image Generation

Generate and edit images using Google's Gemini 3 Pro Image model (gemini-3-pro-image-preview, nicknamed "Nano Banana Pro" 🍌).

Prerequisites

Required:

• GEMINI_API_KEY - Get from Google AI Studio

• Python 3.10+ with google-genai package

Install dependencies:

pip install google-genai pillow

Quick Start

Generate an image:

python3 <skill_dir>/scripts/generate.py "a cute robot mascot, pixel art style" -o robot.png

Edit an existing image:

python3 <skill_dir>/scripts/generate.py "make the background blue" -i input.jpg -o output.png

Generate with specific aspect ratio:

python3 <skill_dir>/scripts/generate.py "cinematic landscape" --ratio 21:9 -o landscape.png

Generate high-resolution 4K image:

python3 <skill_dir>/scripts/generate.py "professional product photo" --size 4K -o product.png

Script Reference

scripts/generate.py

Main image generation script.

Usage: generate.py [OPTIONS] PROMPT

Arguments:

  PROMPT              Text prompt for image generation

Options:

  -o, --output PATH   Output file path (default: auto-generated)

  -i, --input PATH    Input image for editing (optional)

  -r, --ratio RATIO   Aspect ratio (1:1, 16:9, 9:16, 21:9, etc.)

  -s, --size SIZE     Image size: 2K or 4K (default: standard)

  --search            Enable Google Search grounding for accuracy

  -v, --verbose       Show detailed output

Supported aspect ratios:

• 1:1 - Square (default)

• 2:3, 3:2 - Portrait/Landscape

• 3:4, 4:3 - Standard

• 4:5, 5:4 - Photo

• 9:16, 16:9 - Widescreen

• 21:9 - Ultra-wide/Cinematic

scripts/batch_generate.py

Generate multiple images with sequential naming.

Usage: batch_generate.py [OPTIONS] PROMPT

Arguments:

  PROMPT              Text prompt for image generation

Options:

  -n, --count N       Number of images to generate (default: 10)

  -d, --dir PATH      Output directory

  -p, --prefix STR    Filename prefix (default: "image")

  -r, --ratio RATIO   Aspect ratio

  -s, --size SIZE     Image size (2K/4K)

  --delay SECONDS     Delay between generations (default: 3)

Example:

python3 <skill_dir>/scripts/batch_generate.py "pixel art logo" -n 20 -d ./logos -p logo

Python API

You can also use the module directly:

from generate import generate_image, edit_image

# Generate image

result = generate_image(

    prompt="a futuristic city at night",

    output_path="city.png",

    aspect_ratio="16:9",

    image_size="4K"

)

# Edit existing image

result = edit_image(

    prompt="add flying cars to the sky",

    input_path="city.png",

    output_path="city_edited.png"

)

Environment Variables

Variable

Description

Default

GEMINI_API_KEY

Google Gemini API key

Required

IMAGE_OUTPUT_DIR

Default output directory

./nanobanana-images

Features

Text-to-Image Generation

Create images from text descriptions. The model excels at:

• Photorealistic images

• Artistic styles (pixel art, illustration, etc.)

• Product photography

• Landscapes and scenes

Image Editing

Transform existing images with natural language:

• Style transfer

• Object addition/removal

• Background changes

• Color adjustments

High-Resolution Output

• Standard: Fast generation, good quality

• 2K: Enhanced detail (2048px)

• 4K: Maximum quality (3840px), best for text rendering

Google Search Grounding

Enable --search for factually accurate images involving:

• Real people, places, landmarks

• Current events

• Specific products or brands

Best Practices

Prompt Writing

Good prompts include:

• Subject description

• Style/aesthetic

• Lighting and mood

• Composition details

• Color palette

Example:

"A cozy coffee shop interior, warm lighting, vintage aesthetic,

wooden furniture, plants on shelves, morning sunlight through windows,

soft focus background, 35mm film photography style"

Batch Generation Tips

• Generate 10-20 variations to explore options

• Use consistent prompts for style coherence

• Add 3-5 second delays to avoid rate limits

• Review results and iterate on best candidates

Rate Limits

• Gemini API has usage quotas

• Add delays between batch generations

• Check your quota at Google AI Studio

Troubleshooting

"API key not found"

• Set GEMINI_API_KEY environment variable

• Or pass via --api-key option

"No image in response"

• Prompt may have triggered safety filters

• Try rephrasing to avoid sensitive content

"Rate limit exceeded"

• Wait a few seconds and retry

• Reduce batch size or add longer delays

References

• references/prompts.md - Prompt examples by category

• examples/ - Example usage scripts