foreground, where it blends into the
background.
Cut
An instantaneous switch from one video signal
to another.
Dissolve
A transition from one video signal to another
in which one signal is faded down, while the
other is simultaneously faded up. The terms mix
or cross-fade are often used interchangeably
with dissolve.
Dynamic Host Configuration Protocol
An Ethernet protocol where a device, such as
the switcher, is given an IP address by the
network host. This eliminates the need to
manually enter the network parameters and IP
address.
Field
One half of a complete picture (or frame)
interval containing all of the odd, or all of the
even, lines in interlaced scanning. One scan of
a TV screen is called a field; two fields are
required to make a complete picture (which is
a frame).
Frame
One complete picture consisting of two fields of
interlaced scanning lines.
File Transfer Protocol
A network protocol that is used to transfer files
from one host computer to another over a
TCP-based network.
Gain
Gain represents the range of signal values
present in a video signal from a lowest to a
highest point (from black to white for example).
Increasing gain expands this range, while
decreasing gain compresses this range. Clipping
occurs if applied gain changes cause output
signal values to fall outside the allowable range.
Generally, increasing the gain for a specific color
component causes the video signal colors to
become increasingly saturated with that color.
Similarly, decreasing the gain for a specific color
component progressively removes that color
component from the output video signal.
Gamma
Gamma corrections introduce non-linear
corrections to a video signal. A gamma
correction can be described as taking a point on
the output versus input video signal line and
pulling it perpendicularly away from the line.
The result is a Bezier curve between the start,
the new point, and the end point. Generally,
increasing the gamma value adds more of the
component to the video signal in the location of
the gamma offset point. Decreasing the gamma
value reduces the amount of the component in
the video signal in the location of the gamma
offset point. Moving the gamma offset point
allows you to select which part of the input
video signal receives the gamma correction. For
example, if you increase the red gamma
correction to the part of the video signal that
has no red component you will add red to those
areas while having little effect on areas that
already contain a significant amount of red. This
allows you to add a red tint to the image while
minimizing the amount of red-clipping that
occurs.
General Purpose Interface
A simple high/low signal that is used to trigger
an action either on an external device or on the
switcher. A GPI can be an input or an output to
the switcher.
High Definition
A high definition (720p, 1080i, or 1080p/3G)
video signal.
Hue
The characteristic of a color signal that
determines whether the color is red, yellow,
green, blue, purple, etc. (the three characteristics
of a TV color signal are chrominance,
luminance, and hue). White, black, and gray are
not considered hues.
Hue Rotation
Hue rotate affects the color of the entire video
signal by rotating the input video hues. This
produces an output video signal with colors that
are shifted from their original hues. By rotating
colors around the wheel, hue values will shift.
For example, a clockwise rotation where yellows
become orange, reds become magenta, blues
become green. The more rotation applied, the
further around the wheel colors are shifted.
Ultrix Acuity Operation Manual (v10.1) — Glossary • 107