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https://github.com/otdavies/unitychromakey

A simple, yet powerful chromakey / greenscreen solution for Unity. Designed to be used with virtual production.
https://github.com/otdavies/unitychromakey

chroma chroma-key chromakey despill green greenscreen key screen shader unity virtualproduction

Last synced: 10 days ago
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A simple, yet powerful chromakey / greenscreen solution for Unity. Designed to be used with virtual production.

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# 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.



![](Examples/Images/Shia.gif)

![](Examples/Images/Shia2.gif)

![](Examples/Images/Distant.gif)



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



![](Examples/Images/Despill.gif)



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



![](Examples/Images/ReflectiveArmor.png)



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



![](Examples/Images/Controls.png)

![](Examples/Images/Armorguywithoutchroma.png)

![](Examples/Images/Armorguywithchroma.png)



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



![](Examples/Images/DespillWorstCaseExample.gif)



**Example of really poor greenscreen situation + DSLR as webcam:**

![](Examples/Images/1080p30fps.gif)



## 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.