Sony DVS-7300, User Manual

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Chapter 4 Basic Operations for Image Creation
4-39
This section describes the settings for keying operations (excluding chroma
keying) which you can make on the M/E banks. It also describes the settings
for downstream keying on a 3.5-M/E system, or 3-M/E system equipped with
a downstream keyer.
For details of chroma key operations and settings, see Chapter 5.
Overview
A key is a video effect in which a hole is cut in the background video, and
filled with a different video image, or simply a matte if the shape of the hole
corresponds to titling for example. The video signal which cuts the hole,
determining its shape, is termed the key source signal, and the video used to
fill the hole is termed the key fill signal. A component of the system which
carries out keying is called a keyer.
Each M/E bank is provided with two keyers (numbered 1 and 2), and when
using the DMK-7000 Digital Multi Keyer option, an additional maximum of
four downstream keyers (DSK 1 to DSK 4).
Key types
The key type determines the technique used to cut the hole in the background
video. The M/E banks provide the following five key types.
For details of the key types used by the downstream keyer, see the section
“Downstream Keys” (page 4-71).
Luminance key
The hole is cut at a certain level of the Y (luminance) signal of the key
source.
• In a D2 system, the key source is passed through a filter, and the resulting Y
signal is used to determine the key.
• In a D1 system, the key source Y signal is passed through a filter to apply
S-curve compensation, and the resulting signal is used to determine the key.
Keys