From Zoom calls to SciFi effects films -- you can do it all with a DIY chromakey background made from retroreflective fabric, lit with a lens-mounted NeoPixel light ring. A QT Py microcontroller running CircuitPython allows you to control the light ring color and brightness with a push and twist of a rotary encoder knob.

Create chromakey mattes to place your subject in front of any background image or video you like using a retroreflective greenscreen/bluescreen -- you decide the color you need with the press of a knob.

Traditional greenscreen/bluescreen backgrounds are tricky to light evenly, and require a lot of space to prevent your subject from casting shadows and receiving green/blue spill. This retroreflective screen solves all of these problems -- and costs less, too!

This rig works equally well with realtime keyers (built into Zoom, OBS, and others) as well as offline compositing software, such as DaVinci Resolve or iMovie

This technique is used in existing commercial systems, such as the Reflecmedia Chromatte/LiteRing and the LEDChromaKey system.

A friend of mine told me about this technique and said he'd built a DIY version that worked great. I figured NeoPixels would work well for this and my buddy gave me some spare retroreflective screen material to test it out. I did a quick test and found out that it works better than I'd hoped!


Hand holding NeoPixel Ring with 24 x 5050 RGB LED, lit up rainbow
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Animation of Adafruit QT Py with onboard NeoPixel in a rainbow swirl.
What a cutie pie! Or is it... a QT Py? This diminutive dev board comes with our favorite lil chip, the SAMD21 (as made famous in our GEMMA M0 and Trinket M0 boards).This time it...
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Rotary Encoder with rubbery knob
This rotary encoder is the best of the best, it's a high-quality 24-pulse encoder, with detents and a nice feel. It is panel mountable for placement in a box, or you can plug it...
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Opened box showing many nylon screws
Totaling 420 pieces, this M3 Screw Set is a must-have for your workstation. You'll have enough screws, nuts, and hex standoffs to fuel...
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USB Type A to Type C Cable - approx 1 meter / 3 ft long
As technology changes and adapts, so does Adafruit. This  USB Type A to Type C cable will help you with the transition to USB C, even if you're still...
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Silicone Cover Stranded-Core Wire - 26AWG in Various Colors
Silicone-sheathing wire is super-flexible and soft, and it's also strong! Able to handle up to 200°C and up to 600V, it will do when PVC covered wire wimps out. We like this...
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Elastic Band

You'll also need a single #33 size (approx. 3-1/2" x 1/8") rubber or silicone band. I like the silicone hair bands like these.

Retroreflective Fabric

Get a yard or two of retroreflective fabric in either 39" or 49" width. Available most readily on eBay, such as this item or this one

This guide was first published on Mar 10, 2021. It was last updated on Apr 21, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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