Actors are filmed against a background of bright green LEDs while being lit from the front with only red and blue ones, which gives a magental look to the talent.

This technique has the effect of creating a green channel that records only the background. The missing green cannel information for the foreground is then replaced in real time by software, aided by reference photos of the actors.

Netflix invents new green-screen filming method using magenta light - YouTube

Per the demo video, it works surprisingly well. More at the source article here (https://www.newscientist.com/article/2379971-netflix-invents-new-green-screen-filming-method-using-magenta-light/).

Andrew

Interesting. Maybe a spin-off technique of something I first saw about twenty years ago. It used retroreflective sheets for the background and green LEDs on the camera side. The company that first developed the technique that I remember has long gone, I believe, but it worked very well. There are still people playing around with this type of tech. Like this.

Chris Young

Retroreflective Chromakey Greenscreen DIY demo @adafruit @johnedgarpark #adafruit - YouTube

Is This The Simplest Green Screen Setup - Ever? - YouTube

Interesting. Maybe a spin-off technique of something I first saw about twenty years ago. It used retroreflective sheets for the background and green LEDs on the camera side. The company that first developed the technique that I remember has long gone, I believe, but it worked very well. There are still people playing around with this type of tech. Like this.

Chris Young

Retroreflective Chromakey Greenscreen DIY demo @adafruit @johnedgarpark #adafruit - YouTube (https://www.youtube.com/watch?v=I7kWraqKYCk)

Is This The Simplest Green Screen Setup - Ever? - YouTube (https://www.youtube.com/watch?v=MU8U4ohrY7E)
I remember 'Reflecmedia', a company that produced sheets of fabric which comprised micro versions of 'cats eyes' type beads that had a very narrow angle of reflectivity and a natural grey colour. The set was illuminated by a simple LED halo around the camera lens.

Yup! That was them. Had a hunt on Youtube and found this:

Chris Young

Tech Talk: The Reflecmedia Chromatte system - YouTube