nano-banana-image

AI image generation CLI powered by Gemini image models.

Prerequisites

• nano-banana binary in PATH
• GEMINI_API_KEY environment variable

If not set up, see references/installation.md.

Quick Reference

# Basic generation
nano-banana "a cat in a spacesuit"

# High-res widescreen
nano-banana "cinematic landscape" -s 2K -a 16:9

# Transparent asset (no external tools needed)
nano-banana "robot mascot" -t -o mascot

# Style transfer from reference image
nano-banana "apply this style to a forest" -r style.png -o forest

# Pro model for highest quality
nano-banana "detailed portrait" -m pro -s 2K

Options

Option	Default	Description
-o, --output	nano-gen-{ts}	Output filename (no extension)
-s, --size	1K	Image size: 512, 1K, 2K, 4K
-a, --aspect	model default	Aspect ratio: 1:1, 16:9, 9:16, 4:3, 3:4, etc.
-m, --model	flash	Model: flash, pro
-d, --dir	current directory	Output directory
-r, --ref	-	Reference image (repeatable)
-t, --transparent	-	Generate with transparent background
--json	-	JSON output to stdout
--plain	-	Plain output (filenames only)

Models

Alias	Model	Use case
flash	Gemini 3.1 Flash	Default. Fast, cheap
pro	Gemini 3 Pro	Highest quality

Transparent Mode

-t generates on a green screen, then removes the background using built-in colorkey + despill + trim. Pure Go, no ffmpeg or ImageMagick needed.

Cost Tracking

nano-banana --costs
nano-banana --costs --json

Detailed Installation

See references/installation.md.