A Chromakey replaces areas of a selected color within one picture with corresponding areas from a second picture. A common use is the television weather show where a meteorologist stands in front of a green screen. Chromakey will replace the green areas of the meteorologist's picture with corresponding areas of a second picture containing weather graphics. This effect will appear to place the meteorologist in front of the graphics in the resulting picture.
Video Chroma Key, Video Color Key, Color Separation
Overlay, Green or Blue Screen, Background or Backdrop,
Video Compositing & Matting - Model 617S