Glossary
Interlaced
An Interlaced video format starts at the top of
the screen and draws all the odd number scan
lines and then all the even number scan lines
in sequence. This results in half the image being
drawn in one pass and the other half of the
image being drawn in the second. These two
passes are called Fields, where the first pass is
called Field 1 and the second pass is called Field
2. When both Field 1 and Field 2 have been
drawn, resulting in a complete image, you have
a single Frame.
Progressive
A Progressive scan video format draws each
scan line in sequence, starting from the top of
the screen and working to the bottom. Unlike
Interlaced, with Progressive scan the entire
image is drawn at one time, in a single pass. This
means that there are no fields in a Progressive
scan image.
Auto Key
A pairing of two video signals, a key video and
a key alpha, to create a key. In the switcher, you
associate the fill and alpha so that the switcher
knows which alpha to use when the video is
selected.
Auto Transition
An automatic transition in which the manual
movement of the fader handle is simulated
electronically. The transition starts when the
AUTO TRANS
button is pressed and takes place
over a pre-selected time period, measured in
frames.
Chroma Key
Chroma Key is a key in which the hole is cut
based on a color value, or hue, rather than a
luminance value or alpha signal. The color is
removed and replaced with background video
from another source.
Chroma Key Background
Background elements are those pixels in the
source video that are the same color as the one
you chose to key out. Note that the Shadow and
translucent areas (see below) are completely
contained within the Background area.
Chroma Key Edge Softness
Edge Softness lets you apply varying degrees of
softening to the Foreground edges to help it
blend in with the underlying background image
that it is being keyed over.
Chroma Key Foreground
Foreground elements are those pixels that are
not within the Background, Shadow,
Translucency, or Transition ranges. This is the
area with colors that will not be keyed out and
will remain solid.
Chroma Key Luminance
Luminance allows you to control the overall
brightness of Shadow, Translucency, and
Transition areas as well as partial reflections to
more closely match the Foreground brightness.
Chroma Key Shadow
Shadow elements are those pixels in the source
video with colors that are within the
Background range, but with lower luminance
values, depending on the shadow range. You
modify the Shadow range to cover darker areas
of the background (e.g. where the foreground
is casting a shadow on the background screen).
Chroma Key Spill Suppress
Spill Suppression elements are those pixels in
the Foreground that have a noticeable tint of
the Background color. This typically occurs
around the edge of the foreground subject as
glow from the background blue-screen or
green-screen “spills” onto them.
Chroma Key Translucency
Translucent elements are those pixels in the
source video that are in the Background range,
but with higher luminance values than the
Shadow range. You can control the upper-end
of the Translucency range by setting a wider
hue-range to constrain the area. You can also
control the transparency of the Translucent
area.
Chroma Key Transition
Transition elements are those pixels in the
source video with colors that are not within any
of the previous three ranges and are also not
considered part of the Foreground area. These
are typically the pixels near the edge of the
106 • Glossary — Ultrix Acuity Operation Manual (v10.1)