Nanobanana Image Generation Skill

Generate images using Google's Gemini API via the nanobanana CLI tool.

Prerequisites

•

Install nanobanana:

bash

brew tap skorfmann/nanobanana
brew install nanobanana

•
Set your Gemini API key:
bash
```
export GEMINI_API_KEY="your-api-key"
```
Get a key at: https://aistudio.google.com/apikey

When to Use This Skill

Use this skill when the user asks to:

•Generate images from text descriptions
•Create presentation slides
•Design banners, thumbnails, or social media images
•Edit or transform existing images
•Combine multiple images
•Create consistent branded visuals using templates

Basic Commands

Text-to-Image Generation

bash

nanobanana "your prompt here"
nanobanana -o output.jpg "your prompt here"
nanobanana -aspect 16:9 -size 2K -o slide.jpg "your prompt here"

Image Editing (with input image)

bash

nanobanana -i input.jpg "transform into watercolor style"
nanobanana -i photo.jpg "add sunglasses to the person"

Multi-Image Composition

bash

nanobanana -i background.jpg -i subject.jpg "place the subject in the scene"
nanobanana -i template.jpg -i content.jpg "apply the template style"

Options

Flag	Description	Default
`-i <file>`	Input image (repeatable)	none
`-o <file>`	Output filename	auto-generated
`-aspect <ratio>`	Aspect ratio	`1:1`
`-size <size>`	Image size (1K, 2K, 4K)	`1K`
`-version`	Show version	-

Supported Aspect Ratios

1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9

Workflow Patterns

Single Image

bash

nanobanana -o hero.jpg "a futuristic cityscape at sunset, cyberpunk style"

Presentation Slides (Consistent Style)

bash

# 1. Generate a template first
nanobanana -aspect 16:9 -size 2K -o template.jpg \
  "presentation slide template with dark blue gradient, modern minimal style"

# 2. Generate each slide using template as style reference
nanobanana -i template.jpg -aspect 16:9 -size 2K -o slide_01.jpg \
  "using this template style, create a title slide for 'Project Alpha'"

nanobanana -i template.jpg -aspect 16:9 -size 2K -o slide_02.jpg \
  "using this template style, create a slide showing three key features"

Image Editing Workflow

bash

# Generate initial image
nanobanana -o draft.jpg "a logo for a tech startup"

# Refine with edits
nanobanana -i draft.jpg -o final.jpg "make the colors more vibrant and add a subtle glow effect"

Prompting Tips

•Be specific: Include style, mood, colors, composition details
•For edits: Reference "this image" or "keep everything else identical"
•For consistency: Use a template image with -i flag
•For slides: Always use -aspect 16:9 -size 2K

Pricing

•1K-2K images: ~$0.13 per image
•4K images: ~$0.24 per image

Example Prompts

Marketing Banner

bash

nanobanana -aspect 16:9 -size 2K -o banner.jpg \
  "professional marketing banner for a SaaS product launch,
   dark gradient background, glowing tech elements,
   modern minimal design, no text"

App Icon

bash

nanobanana -aspect 1:1 -size 1K -o icon.jpg \
  "app icon for a meditation app,
   soft purple gradient, lotus flower symbol,
   simple flat design, rounded corners style"

Social Media Post

bash

nanobanana -aspect 1:1 -size 2K -o social.jpg \
  "instagram post announcing a new feature,
   bright cheerful colors, confetti elements,
   celebratory mood, tech startup aesthetic"

Troubleshooting

•No GEMINI_API_KEY: Set the environment variable
•Wrong file extension: nanobanana auto-corrects to match actual format (usually .jpg)
•Image too large: Use smaller -size option (1K instead of 4K)

More Information

•Repository: https://github.com/skorfmann/nanobanana
•Examples: https://github.com/skorfmann/nanobanana/tree/main/examples