The purpose of a color keyer is to make a particular color range transparent. This is commonly used in conjunction with a live camera filming a presenter or actor in front of a uniform blue or green background. It may also used in other situations where you have a clean background color that you want to make transparent.
In the example below, a glass of water was filmed against a green background. The video is overlaid on a still image in WATCHOUT. The images show before and after applying the green keyer.
Video shot against a green background, overlaid on a still image.
A green keyer applied to the video.
To try this out, download the attached Chromakey.zip file, unzip it, and open the show file in WATCHOUT.
You may occasionally even use this method to key out the background of a still image, or other image source. However, generally speaking, specialized image editing tools – such as Adobe Photoshop – do a better job of removing backgrounds.
HINT: Use the Selective keyer to key out a solid black, white or other single color background in PowerPoint or similar computer graphics applications. The Selective keyer lets you specify any color, as well as a color tolerance.