Tektronix Grass Valley 3000 - Manual (Page 224)

Appendix A — Shaped and Unshaped Video
A-2
Shaped Video —Fill video that has been “multiplied” by a key
signal to produce a raster image to be inserted into a key hole cut
in background video by the same key signal. (An example of
shaped video is the fill video output of a character generator,
which consists of characters on a black matte.)
Unshaped Video —Previously-shaped fill or composited video
that has been unshaped by an unshaping processor which
“divides” the video by the key signal. The Model 2200, 3000, and
4000 switchers, as well as some Digital Picture Manipulators
(DPMs), have selectable unshaping circuits on their outputs.
Non-Shaped Video —Any full-raster (full-screen) video that
has not previously been processed by a key signal. This is also
sometimes loosely defined as Unshaped Video. Video sources
from devices such as cameras are usually full-raster video and
thus are non-shaped. These sources are not usually accompanied
by key signals.
Input Shaped and Unshaped Video
Video coming into a switcher may or may not already be shaped,
depending upon its source. In the Model 2200, 3000, and 4000
switchers, provision is made in the Configuration menu to define
whether the source video for each video input is shaped or
unshaped. This is what tells the switcher how to process the
signal.
If you incorrectly identify the type of video in the Configuration
menu—that is, if you select shaped when you should select
unshaped, or vice versa—your keys will have dark or light halos
at the edges.