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Appendix A: Glossary
Menu
➤
A list of selectable options displayed on the screen.
NTSC Video
➤
A video output format of some video tape and disk players. There are two types of NTSC
(National Television Standards Committee) video: NTSC 3.58 and NTSC 4.43. NTSC 3.58
is used primarily in North America and Japan. NTSC 4.43 is less commonly used.
Optical Screen
➤
A type of rear-projection screen which re-directs light through the screen to increase
image brightness in front of the screen. Screen gain is usually greater than 1 but audience
viewing angles are reduced.
PAL Video
➤
PAL (Phase Alternating Line) video is a 50 Hz standard with 768 x 576 resolution. It is
found on some video tape and disk players (used primarily in Europe, China and some
South American and African countries).
Pixel
➤
The smallest discernible element of data from a computer-generated image.
Pixel Phase
➤
The phase of the pixel sampling clock relative to incoming data.
Pixel Tracking
➤
The frequency of the pixel sampling clock, indicated by the number of pixels per line.
Projector-to-Screen
➤
Distance
The distance between the projector’s lens and the screen. Also called “Throw Distance”.
Protocol
➤
The syntax used by the communication system.
Pull-down List
➤
A selectable menu item that unfolds into a list of options pertaining to it.
Rear Screen
➤
A translucent panel for screen projection. Incident light travels through the incident surface
of a rear screen and forms an image on the other surface.
Resizing
➤
The ability to manipulate through software commands the physical size, placement and/or
aspect ratio of an image.
Resolution (lens)
➤
The maximum number of alternate white and black horizontal lines that can be
distinguished on a screen when a photographic target is placed between the lens and a
light source and illuminated by that source.
Resolution (projector)
➤
The maximum number of pixels that the projector can display horizontally and vertically
across an image, such as 1024 x 768 (called XGA).
Retrace Time
➤
(Horizontal)
The minimum time required for a CRT projector to move the position of the scanning spot
from the right edge to the left edge.
Rise Time
➤
The time required by the video amplifier of the projector to increase its output from 10% to
90% of the maximum value.
RGB Video
➤
The video output (analog or digital) of most computers. Analog RGB video can have 3, 4,
or 5 wires — one each for red, green, and blue, and either none, one or two for sync. For
three-wire RGB, the green wire usually provides sync. (See TTL Video).
RS-232
➤
A common asynchronous data transmission standard recommended by the Electronics
Industries Association (EIA). Also called serial communication.
RS-422
➤
A less common asynchronous data transmission standard in which balanced differential
voltage is specified. RS-422 is especially suited to long distances.
S-Video
➤
The output from certain video tape players and video equipment. S-Video separates sync
and luminance from color information, typically producing a higher quality display than
composite video.
Scan Frequency
➤
The horizontal or vertical frequency at which images are generated. Also known as scan
rate or refresh rate.
Scan Line
➤
One horizontal line on the display.
Scan Rate
➤
The horizontal or vertical frequency at which images are generated.
