From start to completion, Charlie walks through the basics of achieving a Green Screen effect.
Setting up a chroma key wall like this greenscreen behind me is one of the Holy Grails of video production. Sometimes you just want to replace the background with something different. We'll show you how to do it.
As far as color choices for chromakeying going, green is the most popular choice for video. The biggest reason is that the imaging devices used in camcorders are more sensitive to green than to red or blue. You could use blue instead, but the primary use for blue is film since the blue emulsion layer of film has the finest crystals. Red is generally not used for chromakeying with people because red is too close to a lot of skin colors.
A number of different surfaces can be used for chromakeying. The most permanent is a painted wall. A special matte surface paint is available. This makes for very high quality key effects but it works best with an untextured wall.
Both fabric and heavy paper also work well although they are better suited as temporary surfaces. However, they are also portable. The prices of fabric and of paper vary with the quality of the materials. A good and reasonably inexpensive example of a fabric surface is a bed sheet. Some editing software titles ship with green plastic sheets for chromakeying. These are both temporary and portable but they are often difficult to find on their own.
As far as what your talent can wear while performing in front of a chromakey wall, the only consideration is to avoid wearing the same color that is on the surface of the wall. That is to say, if you've got a green wall, you probably don't want to wear green clothes unless you're shooting for a comedic effect.
For lighting, the basic approach is to use three point lighting. Higher wattage fixtures are preferred. You'll get the best results if you can get the background lit as evenly as possible and to avoid shadows on the surface of the chromakey wall. When you get back to your editing software, the typical approach to creating the actual chromakey effect is implemented by putting the greenscreen video on the first track and the new background image or video on the second track. Apply the chromakey effect to the first track. Select the green area to be removed and adjust the controls to get the cleanest key that you can get. Some editing software also has smoothing, feathering, or anti-aliasing effects that make the finished video look even better.
I hope we've given you all the information and inspiration that you need to do your own chromakey effect. Once you've considered your clothing choices, what kind of background you're using, and you get your light set up correctly, it's a lot of fun. Give it a shot.
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