UnityChromakey

Disclaimer: Unity has changed a lot since I originally implemented this simple shader, it may no longer work as intended in all render pipelines and conditions.

A simple, yet powerful chromakey / greenscreen solution for Unity. Designed to be used with virtual production.

Usage

This shader works in HDRP & URP

Once you've got the files in your project: Assign the chromakey shader to a material of your choice and attach that material to a quad / plane. Provide an image to the material or use a VideoPlayer to feed an image in.

Why this approach? It is the most verstile. Screenspace effects are complicated, clunky and difficult to modify. Screenspace effects also cannot be placed in worldspace easily. This shader is simple, only a few hundred lines and is a single pass. It is excellent for quickly blocking out greenscreen footage or even final composites. This repository is not an entire project. You don't need all my project cruft yuck. This is simply a few files you can toss into your project and actually use.

Features

• Standard Chromakeying: (green screen only). Modification would be required to work with a bluescreen (Would require Despill algorithm changes)
• Simple edge feathering: This is a single-pixel blur approach, but enough for 99% of shots (when do you actually need a crazy 15 pixel deep blur?!?). I will probably expand the kernel to a larger box blur in the future.
• Simple edge sharpening: (Sharpen up blurred edges to give a more anti-aliased feeling as opposed to just blur)
• Despill correction: Getting rid of that pesky green light bleed
• Simple usage, only a single shader and a single-pass
• Example presets you can load onto the material (for the existing examples)

Examples

Note: Have mercy on the GIF compression and the fact that this footage was downloaded from YouTube, so it already has compression artifacts within it. It would look considerably better with nice clean source footage.

Note: This is an example of Despill correction being toggled. Watch the edges for green.

Note: This is reflective armor. Reflective. The nightmare for greenscreen. Looks pretty good to me!

Here are the controls used to tune for the following images:

Note: This is me controlling the strength of the Despill correction.

Example of really poor greenscreen situation + DSLR as webcam:

Modification

You are free to modify and improve on this simple approach. I suggest creating a pull request with your changes!

Primary sources in the creation of this tool

http://gc-films.com/chromakey.html

https://benmcewan.com/blog/2018/05/20/understanding-despill-algorithms/

Disclaimers

Example images are random and off the internet. They are not mine and I don't pretend they are.

This shader hasn't been heavily optimized yet, but appears to perform quite well. It is untested on mobile platforms, but theoretically should work.