How to Create Chromakey Effects in Video

We’ve come a long way since Star Wars. Where the ability to magically insert different video elements together was once the province of special effects studios, with expensive equipment that filled an aircraft hanger, most of us can now create complex and impressive chromakey effects on our home computers.

Chromakey means taking an element, often a colour or range of colours, and making them transparent so a video layer underneath shows instead of that colour. Hence the term Greenscreen where an actor would be filmed in front of a green screen and then the footage would have the shade of green removed leaving just footage of an actor that could then be placed over other footage. Multiple layers of chromakey allow for all manner of impressive effects, such as the multiple flying models from Star Wars superimposed onto a star-field, or several different versions of the same character interacting in one scene.

Key things to remember for good chromakey results are lighting and choice of backdrop.

Lighting – When you remove a colour, your video editing software will have a slider where you can change the range of shade you are removing, so the less variation in shade the better, this means good lighting in front of and behind your subject to avoid casting any shadows on the backdrop.

Choice of backdrop – The colour you remove does not have to be green, the key thing to remember is that you are removing a colour, so avoid any colour that also appears in the element you want to keep. That’s why green is so popular, it’s not present in skin tones or eyes. So it’s no good trying to use greenscreen if you are trying to superimpose a frog or cucumber, or if your actor is wearing a green jumper. You don’t even have to have any sort of fancy greenscreen studio, a clear blue sky is especially effective as it not only gives you a large canvas to work with, but eliminates the problems of shadows, you just have to worry about clouds and birds instead.

Film your segment then apply the chromakey effect, check different segments of the video to make sure your variation is set correctly, then try adding footage behind it. In no time at all you’ll be creating the next Star Wars, or maybe try something else, someone else is already doing the next Star Wars.

[Image via Russ Payne]