nano-banana-image
AI image generation CLI powered by Gemini image models.
Prerequisites
nano-bananabinary in PATHGEMINI_API_KEYenvironment 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.