Green Screen Cutout Assets Skill

A Codex skill for generating foreground image assets on chroma-key backgrounds and converting them into transparent PNGs with a robust local cutout script.

It is useful for app/game/product teams that need stickers, pets, characters, props, collectibles, eggs, UI decorations, or other foreground assets that must sit naturally on top of real app backgrounds.

What It Does

• Guides image-generation prompts for cutout-safe foreground assets.
• Uses a green-screen source image as a stable bridge when true transparent PNG output is unreliable.
• Estimates the actual key color from image borders instead of assuming exact `#00ff00`.
• Removes only edge-connected background regions to reduce accidental subject erosion.
• Applies alpha feathering, despill, cropping, JSON QA reports, and contact sheets.
• Supports single-image and batch processing.

Install

From a local checkout:

Copy-Item -Recurse .\green-screen-cutout-assets "$env:USERPROFILE\.codex\skills\green-screen-cutout-assets"

Or install from GitHub with Codex's skill installer after this repository is published:

python C:\Users\19540\.codex\skills\.system\skill-installer\scripts\install-skill-from-github.py `
  --repo ACT-chao/green-screen-cutout-assets-skill `
  --path green-screen-cutout-assets

Restart Codex after installing new skills.

Quick Use

Generate a source image with a prompt like:

warm hand-drawn journal sticker style, cozy mobile app asset, soft paper texture, pastel warm colors, no hard outline, plain solid chroma green background for cutout, isolated full body centered with generous padding, no shadow touching edges, no text, no watermark

Then run:

python .\green-screen-cutout-assets\scripts\chroma_key_cutout.py `
  --input .\source.png `
  --out .\transparent.png `
  --report .\cutout-report.json `
  --contact-sheet .\cutout-contact-sheet.png

Batch example:

python .\green-screen-cutout-assets\scripts\chroma_key_cutout.py `
  --input-dir public/assets/source-green-screen `
  --out-dir public/assets `
  --report public/assets/cutout-report.json `
  --contact-sheet public/assets/cutout-contact-sheet.png

Output QA

Use the generated report/contact sheet to check:

• transparent corners;
• no obvious green fringe;
• subject not eroded;
• reasonable transparent/opaque ratios;
• fine details such as ears, tails, fur, hands, or props preserved.

Repository Layout

green-screen-cutout-assets/
  SKILL.md
  agents/openai.yaml
  references/prompt-cookbook.md
  scripts/chroma_key_cutout.py

Notes

This repository contains only the reusable Codex skill and cutout helper. Generated source images and app-specific assets should live in your project, not inside the skill.