7. Windowing
7.14 Color key
Color key
Sometimes also called chromakey. This is a method of combining two video images. An ex-
ampleof chroma keying in action is the nightly news person standing in front of a giant weather
map. In actuality, theperson is standing in front of a blue or green background and their image
ismixed with a computer-generated weather map. Thisis how it works: a TV camera is pointed
at the person and fed along with the image of thew eathermap into a box. Inside the box, a
decisionis made. Whereverit sees the blue or green background, it displays the weather map.
Otherwise, it shows the person. So, whenever the person moves around, the box figures out
where he is, and displays the appropriateimage.

Example images of color keying

Takee.g. two image. One taken on a full color background and the other a normal image. The full color
background will be replaced by the second image via theprinciple of color keying.
Image 7-39
Zebraon a singlecolor
Image 7-40
Fullcolor image
Image 7-41
Resultimage after color keying
Start up
1. Click on the ON or OFF button of the Window Input Boxnext to Color key.(image7-42)
The color key window opens with the same status as indicated in the Specialmenu. (image 7-43,
image 7-44)
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