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Glossary
Following is an explanation of some of the terms used in this guide which may
be unfamiliar or which were not explained in the text of this guide itself.
Further information can be obtained by referring to other commercially-
available publications.
Aspect ratio The ratio between an image's length and its height. HDTV images have
an aspect ratio of 16:9 and appear elongated. The aspect ratio for
standard images is 4:3.
Colour
temperature
The temperature of an object which is emitting light. If the colour
temperature is high, the colours tend to take on a bluish tinge. If the
colour temperature is lower, the colours tend to take on a reddish tinge.
Component
video
Video signals which have the video brightness signals and colour
signals separated, in order to provide better image quality.
In high-definition TV (HDTV), it refers to images which consist of
three independent signals: Y (luminance signal), and Pb and Pr (colour
difference signals).
Composite
video
Video signals which have the video brightness signals and colour
signals mixed together. The type of signals commonly used by
household video equipment (NTSC, PAL and SECAM formats).
The carrier signal Y (luminance signal) and chroma (colour) signal
which are contained in the colour bar are overlapped to form a single
signal.
Contrast The relative brightness of the light and dark areas of an image can be
increased or decreased in order to make text and graphics stand out
more clearly, or to make them appear softer. Adjusting this particular
property of an image is called "contrast adjustment".
Cool-down The cooling process for the projector's lamp unit continues even after
the [Power] button on the projector's control panel or the remote control
has been pressed to turn off the lamp. After the lamp turns off, the
cooling fan continues operating, but all button operations are disabled.
The length of time that this is happening is called the "cool-down
period". The cool-down period lasts for about 20 seconds. The actual
time will vary depending on the external air temperature.
Dolby Digital A sound format developed by Dolby Laboratories. Normal stereo is a
2-channel format which uses two speakers. Dolby Digital is a 6-
channel (5.1-channel) system which adds to this a centre speaker, two
rear speakers and a sub-woofer.
HDTV An abbreviation for High-Definition Television. It refers to high-
definition systems which satisfy the following conditions.
• Vertical resolution of 750p or 1125i or greater (p = progressive
scanning , i = interlaced scanning )
• Screen aspect ratio
of 16:9
• Dolby Digital
audio reception and playback (or output)