If you aren’t aware as to what Green Screen or Chroma key compositing is (which is great if you don’t, because of course, this technique is meant to be seamless), our old friend Wikipedia gives quite a good rundown:
“Chroma key compositing, or chroma keying, is a special effects / post-production technique for compositing (layering) two images or video streams together based on color hues (chroma range). The technique has been used heavily in many fields to remove a background from the subject of a photo or video – particularly the newscasting, motion picture and videogame industries. A color range in the top layer is made transparent, revealing another image behind. The chroma keying technique is commonly used in video production and post-production. This technique is also referred to as color keying, colour-separation overlay, or by various terms for specific color-related variants such as green screen, and blue screen.
Chroma keying can be done with backgrounds of any color that are uniform and distinct, but green and blue backgrounds are more commonly used because they differ most distinctly in hue from most human skin colors. No part of the subject being filmed or photographed may duplicate a color used in the background.”
These days computers and algorithms are the kings of this trick, but of course, this is something that has been done in film long before computers ever became mainstream. British presenter and tech personality Tom Scott produced this well oiled little video explaining some of the technique that those video pioneers relied on in the past to get the Green Screen job done:
Given the advanced state of the technology and multitude of commercially available computer software such as Autodesk Smoke, Final Cut Pro, Pinnacle Studio, Adobe After Effects, these days it is quite possible and in fact relatively easy for the average home computer user to create green screen videos – simply by using the “chromakey” function in conjunction with affordable green screen or blue screen kits.
In fact, as Australian comedian Sam Tucker (of Samtime News) goes on to show, you can do your own green screen pretty easily on the cheap:
Cheap but effective! (In other words, if you are a Youtuber, what are you waiting for!)