codex-imagegen

# codex-imagegen — image generation via Codex Delegate image generation to the **Codex CLI**, which has a native `imagegen` system skill (the `image_gen` tool) and can write bitmap assets — sprites, icons, illustrations, game assets, transparent PNGs — directly to disk. Useful when the host agent has no image-generation tool of its own. > Supplementary skill. It depends entirely on Codex's own imagegen capability, so it lives alongside the core review skills rather than being one of them. ## When to use - The user asks to generate/create an image, sprite, icon, illustration, or visual asset. - Pixel art, game assets, UI mockups, transparent backgrounds. - Image generation is wanted but no native `image_gen` tool is available in the current environment. ## When NOT to use - A native image-generation tool is already available. - The asset is better as code (SVG, HTML/CSS). - The task is editing existing local images. ## Prerequisites - `codex` CLI installed and authenticated (`codex --version`). ## Usage ```bash codex exec "Generate <description> and save it to <path>" ``` Always specify an **exact save path**. Example: ```bash codex exec "Generate a pixel art health potion sprite (32x32, transparent background) and save it to ./assets/potion.png" ``` ### Useful flags - `-o result.txt` — capture Codex's final message (the image is still written to the path named in the prompt). - `-i ref.png` — attach a reference image for style consistency (repeatable). - `-C <dir>` — set the working directory; `--skip-git-repo-check` — run outside a git repo. - `-m <model>` — pick a model for higher-quality work. - Background it (`... &`, or in Claude Code `run_in_background: true`) for batches; check the log or just verify the files exist. ### Good prompt structure Be specific about size, style, format, palette, and the exact save path: ```bash codex exec "Generate a game asset: - Type: magic scroll item sprite - Style: pixel art, 16-bit - Size: 32x32, transparent background, PNG - Palette: limited 16 colors - Save to: ./assets/items/scroll-magic.png" ``` ### Batch / sets ```bash codex exec "Generate 5 pixel-art item sprites (sword, shield, potion, coin, key), 32x32, transparent PNG, and save them to ./assets/items/ as sword.png, shield.png, etc." ``` ## Validate the output After generation, verify the files: ```bash ls -lh ./assets/sprite.png # exists? file ./assets/sprite.png # valid PNG? sips -g pixelWidth -g pixelHeight ./assets/sprite.png # dimensions (macOS) ``` ## Troubleshooting - **Fails:** confirm Codex is installed/authenticated (`codex --version`); ensure the target dir exists (`mkdir -p`); try a simpler prompt; add `--json` to see structured errors. - **Poor quality:** be more specific (style, size, detail), provide a reference with `-i`, or try a stronger model with `-m`. ## References - Codex imagegen system skill: `~/.codex/skills/.system/imagegen/SKILL.md` - `codex exec --help`