Digital Television Terms Glossary [0-f]
1080i
1080i refers to the number of interlaced pixel scan lines appearing on a
screen - 1,080. An interlaced screen has 1,080 vertical pixels by 1,920
horizontal pixels. Interlaced scanning "paints" the picture on the
screen by first filling in all the odd-numbered scan lines then filling
in all the even-numbered scan lines. Done very quickly, the eye only
sees one picture on the television. Unlike progressive scanning, which
fills in each line before proceeding to the next line, interlaced
scanning is not as stable and prone to artifacting.
16:9
Ratio of the widescreen television screen. For example, for every 16
inches wide, a 16:9 screen is 9 inches high. Also known as 1.78:1 in the
film world, most movies are shown in 16:9 format, which means that a
movie shown in a theater will be accurately reproduced on a 16:9
widescreen television screen without compression or cropping. Virtually
all plasma, lcd and rear-projection televisions are 16:9 format. In
contrast, traditional televisions are 4:3 ratio.
2/3 Pulldown
Digital technology developed by Faroudja to accurately convert and
display movie pictures filmed at 24 frames per second on the standard
framerate for television broadcasts of 30 frames per second.
3/2 Pulldown
Same as 2/3 pulldown.
4:3
4:3 refers to the standard ratio for traditional televisions. For
example, for every 4 inches wide, a 4:3 screen is 3 inches high.
480i
480i refers to "480 interlaced", a form of standard definition digital
television broadcast that approximates the quality of analog television
but is not considered high definition.
480p
480p refers to "480 progressive", a form of standard definition digital
television broadcast comparable to computer displays but not considered
high definition. Each line of the screen is painted before the next
line.
720p
720p refers to "720 progressive", a form of high definition digital
television that comprises 720 vertical pixels by 1,280 horizontal
pixels. Scanning is done by painting a line of pixels before the next
one is painted. Because of the sequential scanning, 720p is better able
to handle motion and is actually superior to 1080i for that reason.
Analog
Refers to the way cable broadcasts are transmitted directly from the
television wall cable to the television.
Anamorphic
Describes the way 16:9 films are compressed to be shown on a 4:3
television screen with black bars on the top and bottom of the picture.
Anamorphic Downconversion
Processing present in all dvd players where an anamorphic film is
"fitted" onto a 4:3 television screen.
Anti-Reflection Screen Coating
The coating on a television screen which absorbs light and resists its
reflection. Helps to keep the image clear to the viewer.
Artifact
An abnormality in a video image resulting in a temporary, visual
distortion. Also known as "pixelation" since the individual pixels can
be briefly seen.
Aspect Ratio
Refers to the relationship between the width and height of a television
screen. A standard television has an aspect ratio of 4:3 while a
widescreen television has an aspect ratio of 16:9.
Audio Input
Refers to the part of the television where connections to audio
components such as a receiver can be made.
Black Level
Refers to the intensity of black in a picture. If not set correctly,
picture detail quality will be poor in dimly lit scenes of a movie. Also
refers to the ability of the display to produce a dark, deep shade of
black. This is often a problem in plasma and lcd displays.
Burn-in
Refers to an uneven use of pixels caused by excessively bright and
stationary images which results in a permanent ghosted shadow.
Cathode Ray Tube
The classic-type television with an electron gun at the back of a vacuum
enclosure.
Chrominance Signal
Technical name for the signal that carries the color information (red,
green and blue) required to display a color image.
Color Temperature
Otherwise called white balance, color temperature is expressed in
degrees kelvin or just Kelvins. Color temperature refers to the color of
gray at different levels from black to white. Since color information
overlays the black-and-white information in a TV signal, color
temperature affects the entire range of color. The National Television
Standards Committee (NTSC) standard is 6,500K, but typically
manufacturers ship their TVs with color temperatures ranging from about
7,000K to 12,000K, on the blue side of the color spectrum, to make sets
as bright as possible to stand out on a brightly lit showroom sales
floor.
Comb Filter
Component in all televisions that separates the color information in a
signal from the brightness information.
Component Video Input [Y, PB(CB), PR(CR)]
A type of superior video input used for DVD players and some game
consoles. Picture quality is superior to s-video, composite and
antenna-in.
Compression
Refers to the reduction in the number of bits required to store or
transmit data. The method adopted for digital television is called
MPEG-2.
Contrast Ratio
The brightness of a display at full white over the brightness of a
display at full black. Because the black value is greatly affected by
ambient light, some TV technologies calculate contrast ratio in darkened
rooms.
Digital Cable Ready
Official term for a high definition television that conforms to
plug-and-play digital cable TV standard using "point of deployment"
access cards (a/k/a CableCARDs). A digital cable ready-TV allows users
to plug the cable directly into an HDTV set and enjoy HDTV and digital
cable without having to use a separate set-top box. If there is also
interactive functionality built into the set, it is labeled Interactive
Digital Cable Ready.
Digital Comb Filter
See comb filter definition.
Digital Light Processing (DLP)
Technology developed by Texas Instruments that is based on a digital
micromirror device (a chip with millions of microscopic, hinged
mirrors). Red, green and blue light is filtered through a color wheel
and directed alternately onto the DMD, which switches on and off up to
5,000 times a second. The reflected light is directed through a lens and
onto a screen, creating the image. High end HDTV projectors use three
DMDs and forgo the color wheel--each DMD corresponds to a separate color
(red, green and blue).
DirecTV
A major satellite television provider which broadcasts several channels
in high-definition.
Dish Satellite TV
Another major satellite television provider which also broadcasts
several channels in high-definition.
Dolby Digital (AC-3)
Refers to the standard under which digital surround sound is broadcast.
Dolby Digital is a 6-channel standard corresponding to a center channel,
two side front channels, two rear side channels and a subwoofer channel.
Down Convert
Refers to the conversion of a high-resolution broadcast to a lower
resolution broadcast. For example, some DTV receivers can be set to
downconvert an HDTV 1080i signal to a standard 480i signal that any TV
can display.
DTV
DTV is the acronym for Digital Television. Digital television comes in
three, increasing quality standards: standard definition, enhanced
definition and high definition.
DVI Interface
Digital Visual Interface - a type of standard connector between the
display and a computer or other device. DVI images are superior to
composite video and s-video signals.
DVR
Refers to "digital video recorder", also known as "personal video
recorder". A DVR or PVR records broadcasts on a hard disk drive which
can then be played back at a later time (this is known as "time
shifting"). The most well known DVR is the TiVo.
EDTV
Refers to enhanced definition television. EDTV is a broadcast standard
that produces 852x480 pixel resolution images. EDTV broadcasts are
superior to standard definition broadcasts but not as good as high
definition broadcasts.
EPG
Refers to "electronic programming guide". This feature is found on
satellite and cable tuner boxes and DVRs, and increasingly on TVs and
DVD recorders and provides an onscreen listing of available channels and
program data for an extended time period (e.g. 36 hours or more).
F.C.C.
Federal Communications Commission - Federal governmental agency
responsible for the regulation of broadcast television in the United
States.
Flat Panel Television
Term used to refer to televisions that are modularly thin. Plasma screen
displays and LCD TVs are the two types of flat panel televisions.
Flat Screen Television
Term used to refer to televisions whose display screen is "flat" instead
of curved at corners and edges.
Frame Rate (FPS)
Refers to the number of individual still pictures that pass by every
second to create a moving image. Films run at 24fps, while video,
including DVD, runs at 30fps. To compensate for the difference, 2:3
pull-down detection is used.
Front Projection
Type of television system whereby an image is projected onto a screen or
a wall. The image size is variable depending on the distance of the
projector from the screen or wall.
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