imagegen

Simple Go CLI for generating branded images.

Models

• google/gemini-2.5-flash-image
• openai/gpt-5-image-mini

Setup

1. Set your OpenRouter API key:

export OPEN_ROUTER_API_KEY=your_key_here

2. Install dependencies:

make install

3. Build binaries and web assets:

make build

Optional frontend lint + type-check:

make web-lint
make web-typecheck

Usage

Generate with both models:

./imagegen -prompt "A clean launch announcement banner for a fintech app"

Generate with a single model and brand directory:

./imagegen \
  -prompt "Hero image for homepage, modern and friendly" \
  -brand-dir ./brand \
  -model openai \
  -image-size 2K \
  -aspect-ratio 3:2 \
  -out ./generated

Flags

• -prompt (required): short image prompt
• -brand-dir (optional): directory with text files describing brand guidelines
• -model: google, openai, or both (default: both)
• -out: output directory (default: output)
• -image-size: image size 1K, 2K, or 4K (default: 1K, used by Gemini image model)
• -aspect-ratio: optional ratio: 1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9
• -n: number of images per selected model (default: 1)
• -output-format: output format jpg, png, webp, or ico (default: jpg)
• -ico-sizes: comma-separated ICO sizes from 16x16, 32x32, 48x48 (default: 16x16,32x32,48x48)

Notes

• The CLI reads non-binary UTF-8 files from -brand-dir (top-level only).
• Files larger than 512KB are skipped.
• Generated files are saved with model + UTC timestamp in the filename.
• When -output-format ico is used, generation is forced to 1:1 and encoded with the sizes selected in -ico-sizes.

Web App (Scaffold)

Run the local web app server in dev mode (builds first):

make dev

Optional overrides:

make dev ADDR=:9090 DATA_DIR=/tmp/imagegen-dev

Direct run after make build:

./imagegen-web -addr :8080 -data-dir ~/.imagegen

Web app persistence:

• SQLite metadata database: ~/.imagegen/imagegen.db
• Generated image files: ~/.imagegen/images/...

Long-running generate actions are processed asynchronously:

• Submit from a work item page
• Track status in /jobs
• Inspect failures in /jobs/{id}