image-gen

Image Generation & Editing

Multi-provider image generation. Default provider is Gemini (nano-banana-pro); pass --provider openai to use gpt-image-2.

Which provider to pick

• Gemini (default): general illustrations, quick diagrams, visual imagery.
• OpenAI: anything where text rendering matters (infographics, slide-like images, dense-label diagrams, logos with text) or when you need masked inpainting on edits.

Usage

The skill ships a pre-bundled Node script — no tsx or dependency install required on the user side. Invoke with node. Run node ${CLAUDE_PLUGIN_ROOT}/skills/image-gen/dist/generate_image.js --help at any time for the full flag reference printed by the script itself.

Generate:

node ${CLAUDE_PLUGIN_ROOT}/skills/image-gen/dist/generate_image.js \
  --prompt "your description" --filename "output.png" \
  [--provider gemini|openai] [--resolution 1K|2K|4K] [--size WxH] [--quality low|medium|high|auto] [--api-key KEY]

Edit (image-to-image): node ${CLAUDE_PLUGIN_ROOT}/skills/image-gen/dist/generate_image.js
--prompt "editing instructions" --filename "output.png"
--input-image "path/to/input.png" [--mask "path/to/mask.png"]

## Flag reference

| Flag | Values | Notes |
|------|--------|-------|
| `--prompt` | text | Required. |
| `--filename` | path | Required. Output PNG. |
| `--provider` | `gemini` \| `openai` | Default: `gemini` (or `openai` if only `OPENAI_API_KEY` is set). |
| `--resolution` | `1K` \| `2K` \| `4K` | Default `1K`. `4K` clamps to `3840x2160` on OpenAI. |
| `--size` | `WxH` | OpenAI only. Overrides `--resolution`. Max edge 3840, multiples of 16. |
| `--quality` | `low` \| `medium` \| `high` \| `auto` | OpenAI only. Default `auto`. Ignored on Gemini. |
| `--input-image` | path | Switches to edit mode. Repeatable on Gemini for multi-image composition; OpenAI accepts only one. |
| `--mask` | path | OpenAI only. Inpainting mask. Requires `--input-image`. |
| `--api-key` | key | Overrides env for selected provider. |
| `-h`, `--help` | — | Print CLI help and exit. |

## Resolution

- `1K` (default) — 1024px
- `2K` — 2048px
- `4K` — 4096px on Gemini; silently clamped to `3840x2160` on OpenAI (OpenAI's hard cap is 3840).
- `--size WxH` (OpenAI only) overrides `--resolution`. Max edge 3840, both edges must be multiples of 16.

## Quality (OpenAI only)

`low | medium | high | auto` (default `auto`). Ignored on Gemini with a warning.

## Masks (OpenAI only)

`--mask <path>` enables inpainting. Requires `--input-image`. Error if used with Gemini.

## API keys

Resolution order:
1. `--api-key` flag (applied to selected provider)
2. Provider-specific env:
   - Gemini: `GEMINI_API_KEY` or `GOOGLE_API_KEY`
   - OpenAI: `OPENAI_API_KEY`

## Filename convention

YYYY-MM-DD-HH-MM-SS-descriptive-name.png

For blog diagrams

Use OpenAI at 2K for anything with readable labels or callouts. Save to the appropriate content dir (e.g., src/content/blog/post-name/). Prefer clean, minimalist styles.

Output

• Saves PNG to the specified path.
• Script prints the full saved path.
• Do not read the image back — inform the user of the path.