nano-banana

Original：🇺🇸 English
Translated

Generates AI images using the nano-banana CLI (Gemini 3.1 Flash default, Pro available). Handles multi-resolution (512-4K), aspect ratios, reference images for style transfer, green screen workflow for transparent assets, cost tracking, and exact dimension control. Use when asked to "generate an image", "create a sprite", "make an asset", "generate artwork", or any image generation task for UI mockups, game assets, videos, or marketing materials.

2installs
Sourcekingbootoshi/nano-banana-2-skill
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NPX Install

npx skill4agent add kingbootoshi/nano-banana-2-skill nano-banana

Tags

Translated version includes tags in frontmatter
ai-image-generationcli-toolgeministyle-transferimage-editing

SKILL.md Content

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nano-banana

AI image generation CLI. Default model: Gemini 3.1 Flash Image Preview (Nano Banana 2).

/init - First-Time Setup

When the user says "init", "setup nano-banana", or "install nano-banana", run these commands to get the CLI tool on their machine. No sudo required.
Prerequisites: Bun must be installed. If not: 
curl -fsSL https://bun.sh/install | bash
bash
# 1. Clone the repo
git clone https://github.com/kingbootoshi/nano-banana-2-skill.git ~/tools/nano-banana-2

# 2. Install dependencies
cd ~/tools/nano-banana-2 && bun install

# 3. Link globally (creates `nano-banana` command via Bun - no sudo)
cd ~/tools/nano-banana-2 && bun link

# 4. Set up API key
mkdir -p ~/.nano-banana
echo "GEMINI_API_KEY=<ask user for their key>" > ~/.nano-banana/.env
After init, the user can type 
nano-banana "prompt"
from anywhere.
If 
bun link
fails or the command is not found after linking, fall back to:
bash
mkdir -p ~/.local/bin
ln -sf ~/tools/nano-banana-2/src/cli.ts ~/.local/bin/nano-banana
# Then ensure ~/.local/bin is on PATH:
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc
Get a Gemini API key at: https://aistudio.google.com/apikey

Quick Reference

  • Command: 
    nano-banana "prompt" [options]
  • Default: 1K resolution, Flash model, current directory

Core Options

OptionDefaultDescription
-o, --output
nano-gen-{timestamp}
Output filename (no extension)
-s, --size
1K
Image size: 
512
, 
1K
, 
2K
, or 
4K
-a, --aspect
model defaultAspect ratio: 
1:1
, 
16:9
, 
9:16
, 
4:3
, 
3:4
, etc.
-m, --model
flash
Model: 
flash
/
nb2
, 
pro
/
nb-pro
, or any model ID
-d, --dir
current directoryOutput directory
-r, --ref
-Reference image (can use multiple times)
-t, --transparent
-Generate on green screen, remove background (FFmpeg)
--api-key
-Gemini API key (overrides env/file)
--costs
-Show cost summary

Models

AliasModelUse When
flash
, 
nb2
Gemini 3.1 FlashDefault. Fast, cheap (~$0.067/1K image)
pro
, 
nb-pro
Gemini 3 ProHighest quality needed (~$0.134/1K image)

Sizes

SizeCost (Flash)Cost (Pro)
512
~$0.045Flash only
1K
~$0.067~$0.134
2K
~$0.101~$0.201
4K
~$0.151~$0.302

Aspect Ratios

Supported: 
1:1
, 
16:9
, 
9:16
, 
4:3
, 
3:4
, 
3:2
, 
2:3
, 
4:5
, 
5:4
, 
21:9
Use 
-a
flag: 
nano-banana "cinematic scene" -a 16:9

Key Workflows

Basic Generation

bash
nano-banana "minimal dashboard UI with dark theme"
nano-banana "cinematic landscape" -s 2K -a 16:9
nano-banana "quick concept sketch" -s 512

Model Selection

bash
# Default (Flash - fast, cheap)
nano-banana "your prompt"

# Pro (highest quality)
nano-banana "detailed portrait" --model pro -s 2K

Reference Images (Style Transfer / Editing)

bash
# Edit existing image
nano-banana "change the background to pure white" -r dark-ui.png -o light-ui

# Style transfer - multiple references
nano-banana "combine these two styles" -r style1.png -r style2.png -o combined

Transparent Assets

bash
nano-banana "robot mascot character" -t -o mascot
nano-banana "pixel art treasure chest" -t -o chest
The 
-t
flag automatically prompts the AI to generate on a green screen, then uses FFmpeg 
colorkey
+ 
despill
to key out the background and remove green spill from edge pixels. Pixel-perfect transparency with no manual prompting needed.
Requires: 
brew install ffmpeg imagemagick

Exact Dimensions

To get a specific output dimension:
  1. First 
    -r
    flag: your reference/style image
  2. Last 
    -r
    flag: blank image in target dimensions
  3. Include dimensions in prompt
bash
nano-banana "pixel art character in style of first image, 256x256" -r style.png -r blank-256x256.png -o sprite

Reference Order Matters

  • First reference: primary style/content source
  • Additional references: secondary influences
  • Last reference: controls output dimensions (if using blank image trick)

Cost Tracking

Every generation is logged to 
~/.nano-banana/costs.json
. View summary:
bash
nano-banana --costs

Use Cases

  • Landing page assets - product mockups, UI previews
  • Image editing - transform existing images with prompts
  • Style transfer - combine multiple reference images
  • Marketing materials - hero images, feature illustrations
  • UI iterations - quickly generate variations of designs
  • Transparent assets - icons, logos, mascots with no background
  • Game assets - sprites, backgrounds, characters
  • Video production - visual elements for video compositions

Prompt Examples

bash
# UI mockups
nano-banana "clean SaaS dashboard with analytics charts, white background"

# Widescreen cinematic
nano-banana "cyberpunk cityscape at sunset" -a 16:9 -s 2K

# Product shots with Pro quality
nano-banana "premium software product hero image" --model pro

# Quick low-res concept
nano-banana "rough sketch of a robot" -s 512

# Dark mode UI
nano-banana "Premium SaaS chat interface, dark mode, minimal, Linear-style aesthetic"

# Game assets with transparency (green screen auto-prompted)
nano-banana "pixel art treasure chest" -t -o chest

# Portrait aspect ratio
nano-banana "mobile app onboarding screen" -a 9:16

API Key Setup

The CLI resolves the Gemini API key in this order:
  1. --api-key
    flag
  2. GEMINI_API_KEY
    environment variable
  3. .env
    file in current directory
  4. .env
    file next to the CLI script
  5. ~/.nano-banana/.env
Get a key at: https://aistudio.google.com/apikey