Background - the image or sequence that will replace the backing color. Backing - the blue or green screen area behind the foreground subject.Composite- the combination of multiple images to form a new image containing elements from each. The foreground image (with the backing and flare removed) combined with the background. Flare (blue spill) - contamination of the foreground subject matter with blue or green reflected light from the backing. Foreground - the subject matter against the backing color. Garbage Matte - a matte or alpha channel used to mask out areas of "garbage" which are unwanted in the final composite. Incident Light Meter - an insturment that measures how much light is falling on the meter. Matte - a grey scale image that is used to determine the percentage of foreground and background values which will be displayed. (eg. Alpha channel) Print Thru - areas of the background that are visible through the foreground subject which should not be seen, or, to look at it another way, areas of the foreground subject which are not opaque but should be. Processed Foreground - the foreground image with the backing color suppressed to black and all flare removed. Waveform Monitor - a device that displays the luminance information in a video signal. Measured in IREs.