Greenkey

Greenkey is a fully local reference and calculator for setting up and troubleshooting a chroma-key (green-screen) shoot — the kind of practical, technical guidance a gaffer or video editor would otherwise piece together from several production guides.

What it does

• Lighting setups — 4 backdrop lighting setups (two-light basic, four-light even wall, diffused natural window light, budget clamp-light setup), each with concrete key points, including the commonly cited guideline of keeping backdrop brightness readings within about half a stop of each other for a clean key.
• Lighting evenness check — lighting_evenness_check takes brightness readings you measured across the backdrop (light-meter stops, or a relative/percentage scale) and computes the spread, checking it against the half-stop guideline with a clear verdict. This is computed directly from the numbers you supply — nothing is read from an image or camera.
• Spill suppression — 6 techniques (subject distance, a dark non-reflective floor, not over-lighting the backdrop, a rim/hair light, wardrobe avoidance, reducing the lit screen area, and software despill), each with why it works.
• Backdrop material comparison — backdrop_material_guide compares 6 materials (plain muslin, stretch digital fabric, dyed cotton, vinyl/PVC panel, collapsible pop-up screen, painted cyc wall) on cost, portability, pros and cons.
• Green-vs-blue decision helper — color_choice_guide explains why green is the common default (sensor detail, brightness) and when blue is the better call, and, given a list of the subject's wardrobe colors, computes whether they conflict with green, blue, or both, and recommends accordingly.
• Troubleshooter — troubleshoot takes a symptom (green fringing, a blotchy/patchy key, visible shadows on the backdrop, fine hair or detail not keying, visible wrinkles, spill on skin tones) and returns likely causes and concrete fixes.
• Checklist & glossary — a practical pre-shoot checklist, and a glossary of core terms (chroma key, luma key, spill, despill, garbage matte, edge/holdout matte, choke, key light, wrap/rim light, cyclorama).

How it works

Lighting, spill, material, color-choice, troubleshooting and glossary content is hand-curated original synthesis, checked against current production and lighting references (cited per entry) as of the date shown in each response. lighting_evenness_check and the wardrobe-conflict part of color_choice_guide are original local computed logic that runs entirely on the numbers or colors you provide.

What it deliberately is not

Greenkey never reads or inspects an actual photo, video, or camera feed — it works from readings and descriptions you type in, and from a bundled reference dataset. It gives general craft guidance, not a substitute for testing your specific camera, lens, and compression pipeline before a real shoot. There are no accounts, no uploads, and nothing is stored between requests.