Chapter 4 Keys; Overview; Key Types - Sony MVS-3000 System 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 switcher bank has four keyers.
Notes
If using a DME wipe with background selected for the next
transition on the M/E bank, KEY1 cannot be used.
Similarly, DSK1 cannot be used with DME wipes on the
PGM/PST bank. You select whether to enable KEY1
(DSK1) or DME wipes in the Setup menu
Keyers that support resizer/key edge
The resizer and key edge functions can be used by
following keyers.
• Keys 1 and 2 of the M/E bank
• DSK1 and DSK2 of the PGM/PST bank

Key Types

The key type indicates the manner in which the key source
signal is used to cut out the background.
Type Description
Luminance The background is cut out
key 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.
62
Overview
Type
Color vector
key
Chroma key
Key wipe
pattern key
(1 p. 241).
Clean mode
In a luminance key, linear key or color vector key, you can
turn clean mode on. When clean mode is on, key fill is
added to the background without cutting out with key
source. 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,
Note that in the following situations, the clean mode is
turned off, and cannot be turned on.
• When the key type is a pattern key
Clean
• When key inversion is on
mode
• When the key fill is a matte
Can be
• When the key edge is an outline
used
• When the key edge is normal with soft edge being on
• When fine key is on
• When the key positioner is on
Can be
used
4
Chapter
Description
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.
A key signal based on a particular
color is used to cut out the
background, and the key fill is
then inserted.
This uses the wipe pattern
selected for an independent key
transition to cut out the
background and insert the key fill.
1 "Setting the key type in a menu" (p.
Clean
mode
Can be
used
Cannot
be used
Cannot
be used
65).