Chapter 4 Keys; Overview; Key Types; Luminance Key - Sony MVS-8000X User Manual

Keys

Overview

A key is an effect in which a part of the background image
is replaced by an image or superimposed text. The signal
determining how the background is cut out is termed "key
source," and the signal that replaces the cut-out part is
termed "key fill."
The system component responsible for processing a key is
referred to as a keyer.
Each M/E bank and the PGM/PST bank has eight keyers,
and all of these keyers provide the same functions.
Notes
When the signal format is 1080P, four keyers can be used
(keys 1 to 4).

Key Types

The key type indicates the manner in which the key source
signal is used to cut out the background. In each bank, you
can use the following key types. You can select the key
type using the key type selection buttons in the key control
block, or by a setting in the Type menu for the keyer (see
page 93).

Luminance key

The background is cut out according to the luminance (Y)
of the key source signal, and at the same time the key fill
signal is cut out and then added to the background signal.

Linear key

This is a type of luminance key, but there is a reduced
variability in gain, allowing more precise adjustment.
Chapter
Color vector key
The key signal is created from a combination of the
luminance and chrominance components of the key source
signal. When perfect keying is not possible with a
luminance key, this allows a key signal to be created even
if the luminance level is low, provided that the colors have
high saturation.
Clean mode
In a luminance key, linear key or color vector key, you can
enable the clean mode. When the clean mode is on, the key
source does not affect the key fill, which is added
unchanged to the background. This improves the keyed
image quality, but means that the part of the key fill signal
which is not to be inserted must be completely black, or it
will color the background. You set the clean mode with the
Type menu of the respective keyer.
For details, see "Setting the key type in a menu" (page 93).
Note that in the following situations, the clean mode goes
off, and cannot be turned on.
• When the key type is a pattern key
• When key inversion is on
• When the key fill is a matte
• When the key edge is an outline
• When the key edge is normal with soft edge being on
• When fine key is on
• When the key positioner is on
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Overview