Chroma Key, or it’s more common name “Green Screen”, is a well known aspect in movies and other films. With this technology it is possible to remove the background from a subject, allowing the subject to be placed in any number of new backgrounds. It is also commonly used to create many special effects and even in video games to create motion capture for character animation. Many people do not know that Chroma Key can also be used in photography, however.
Photography based chroma key uses the same principles as in movies and video games, you remove the background, leaving only the subject. This principal has made chroma key very interesting to photographers, especially those who are trying to move from amateur to professional. If you haven’t quite figured out why this interest photographers as much as it does, here is the reason: Chroma key photography allows a photographer to shoot a subject against any background, without utilizing excessive amounts of space or changing backgrounds.
Setting up a chroma key can be an adventure for anyone who has never done it before. It is not a very difficult however, and only requires a few simple steps.
1) True Chroma Key
This is where a lot of photographers mess up, before they ever even turn on their lights. You want to make sure you have a true chroma key before you start shooting. A true chroma key background will be either a solid green or blue, with absolutely no variance in the color or weave of the material. You cannot use just any green fabric or material; you need the constant color and hue of the chroma key. These hues are called “True Green” and “True Blue”.
To better aid with chroma key photography, you can use a darker variant of these true colors. By using a darker variant you can prevent washout when lighting your subject and background. This will aid you by allowing easier separation of the background and the subject.
2) Determine which chroma key color you need
There are two types of chroma keys: Blue and Green. Most people do not realize this, and if you plan to shoot chroma key backgrounds it is something you need to know. The reason there is, and why you should have both colors is simple. When you shoot on a green screen, you are essentially removing all of the constant green from the photo. Therefore, if your subject has green on, parts of your subject will be removed. In this instance you should shoot on the blue screen. Opinions on which screen is better, tend to vary. But overall blue is typically considered a better background for strictly people oriented photography.
3) Obtain all the necessary equipment before hand
When shooting chroma key, there is a very specific set of basic equipment you will need. This includes a True Green or True Blue background, a lighting scheme with at least two lights dedicated to the background, and an editing software that supports chroma key separation.