Monday, June 28, 2021

A $4 Green Screen for Zoom Background

Tom Worthington
in chroma key body suit,
without hood, so just face shows
For the last year and a half I have been giving workshops from home, via Zoom, for students in Australia, also presenting a series of seminars for educators in North America. The background in my lounge/office is a wall, with a couple of posters, must be getting very familiar to people. Zoom has the option to replace the background with a photo, or even your presentation slides, but this works best with a uniformly colored background. Zoom recommends a green background. 

Tom Worthington in
chroma key body in front of green screen

This techniques is called Chroma key, where a specific color in an image is replaced with another image. While any color works, there are two standard ones used in the video industry, a bright green and a bright blue. If you use the standard colors, you can use props which match and will disappear into the background. An extreme example is having a person disappear.

Tom Worthington
in chroma key body suit
with hood covering face
Chroma key color cloth is commonly available for sale online. Recently I found a green chromakey bodysuit at a secondhand store. This is used for special effects. Covering the entire body, including hands and face, with the matching background, the wearer disappears. This could be used by assistants who need to walk on set or to make objects appear to move on their own. Those running online invigilated exams need to keep in mind the suit could be used to hide someone helping the student.

Tom Worthington
using the green screen
in normal clothes
Apple colored
Top Pop Poplin
from Spotlight
Being impatient to try out a green screen, I went to a local haberdashery store and purchased some green cloth (2 m of Apple colored Top Pop Poplin, from Spotlight, at $2 per m). I then clipped this to my room screen.  With a width of just under 2m and a height of 1.16 m this was enough to fill the background for the camera. This cloth is a little darker than the usual chroma key green, but worked well.

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