Tektronix Grass Valley 3000 - Manual (Page 124)

3-16
Section 3 — Switcher Concepts
Chroma Key
A chroma key is a key in which a particular color that you select in
the background of a scene is detected and replaced with a new
background scene. This gives the illusion that foreground objects
are positioned in front of a new background. For example, the fill
video selected on the Key bus may be a weather reporter standing
in front of a blue wall, and the new background video may be a
weather map (
Figure 3-3 ). The completed chroma key consists of
the weather map background where the blue wall used to be and
the reporter foreground fill everywhere else. This creates the
illusion that the reporter is standing in front of the weather map.
A convenient feature of the chroma keyer is automatic setup. This
feature sets up the key for you when you identify the background
color that you want to replace. You simply position a cursor over
the color using the joystick and press the
AUTO SETUP button in
the Chroma Key/Chroma Key Setup Menu. (On the Model 2200,
you can use the
AUTO SETUP button on the Chroma Keyer
Subpanel.) (On the Model 4000-2A, you can use the AUTO SETUP
button on the Chroma Keyer Subpanel.) In most cases, this
function yields a very good chroma key, which you can use as is
or to fine tune as desired using the Keyer controls and the Chroma
Key Menu controls.