Projectors
Hdtv Glossary
HDTV Glossary
3:2 Pull Down
3:2 pull down is a process by which
manufacturers add six frames to film’s original 24-frames-per-second format so
that it can work within the NTSC standard, which is 30 fps. This helps keep the
action from stuttering on your television.
4:3
4:3 is an aspect ratio of traditional squarish
National Television Systems Committee (NTSC) TV screens; it stands for four
units of width for every three units of height.
16:9
16:9 is an aspect ratio of movie screen and
widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV
(Standard Definition TV); it stands for 16 arbitrary units of width for every 9
arbitrary units of height.
24P
Terminology for 24 full frames per second
digital video progressively captured. In most cases it refers to the HD picture
format of 1920x1080, though it is also used with 1280x720 images as well. Often
used to loosely describe a capture system that operates at 23.976P as well.
480p
480p means that the resolution of the picture is
852 vertical pixels by 480 horizontal pixels and p stands for progressive
scanning. Although 480p is in the wide-screen format, it is not considered a
high definition format. It is related to EDTV and current DVD's.
720p
720p means that the resolution of the picture is
1,280 vertical pixels by 720 horizontal pixels and p stands for progressive
scanning. Progressive scanning offers a smoother picture as 720 horizontal
lines are scanned progressively or in succession in a vertical frame that is
repeated 30 times a second.
1080i
1080i means that the resolution of the picture
is 1920 vertical pixels by 1080 horizontal pixels and i stands for interlaced
scanning. Interlaced scanning is based on the principle that the screen shows
every odd line at one scan of the screen and then all the even lines in a
second scan.
1080p
1080p means that the resolution of the picture
is 1,920 vertical pixels by 1,080 horizontal pixels and p stands for
progressive scanning. This format works on the same principle as 720p; the only
difference is that in this type there are more pixels and the resolution is
better.
AC-3
The 5.1-channel sound system specified in the
Standard for Digital-HDTV. Also known as "Dolby Digital," AC-3
delivers CD-quality digital audio and provides five full-bandwidth channels for
front left, front right, center, surround left and surround right speakers,
plus an LFE (low-frequency effect) subwoofer, for a total of 5.1 channels.
A/D
Analog to digital conversion. Used at transmission
end of broadcast.
Advanced Television Systems Committee (ATSC)
Advanced Television Systems Committee is
responsible for establishing and developing digital television standards, as
well as all 18 formats of Digital TV.
Addressable Resolution
The highest resolution signal that a TV or
monitor can accept. It is important to note that while a particular device
(Digital-HDTV) is able to receive the resolution, it may not be capable of
displaying it.
Analog TV
Analog technology has been in use for the past
50 years to transmit conventional TV signals to consumers. "Standard"
television broadcasts in analog TV. Analog signals vary continuously, creating
fluctuations in color and brightness.
Anamorphic video
Video images that have been "squeezed"
to fit a video frame when stored on DVD. These images must be expanded
(un-squeezed) by the display device. An increasing number of TVs employ either
a screen with 16:9 aspect ratio, or some type of
"enhanced-for-widescreen" viewing mode, so that anamorphic and other
widescreen material can be viewed in its proper proportions. When anamorphic
video is displayed on a typical TV with 4:3 screen size, the images will appear
unnaturally tall and narrow.
Artifacts
Artifacts are defined as unwanted visible
effects in the picture caused by disturbances and errors in the video
transmission or digital processing. Artifacts include “edge crawl” or “dot
crawl” or “hanging dots” in analog pictures, and “pixelation”, “contouring” or
“blockiness” in digital pictures.
Aspect ratio
Aspect ratio is ratio of width to height of a TV
screen. It may be either traditional squarish 4:3 ratio of the National
Television Systems Committee (NTSC) TV screen or 16:9 ratio of widescreen DTV
formats for all HDTV (High Definition) and some SDTV (Standard Definition).
ATSC
An acronym for Advanced Television Systems
Committee, which is responsible for developing and establishing Digital-HDTV
Standards; and the name of the DTV system used by broadcasters in the U.S.
Bandwidth
Bandwidth, in general, means amount of
information that can be carried in a given time period (usually a second). More
exactly, it is a range of frequencies used for transmitting picture and sound
information from transmitter to your TV. Federal Communications Commission
(FCC) has allocated 6 MHz for TV broadcasters for each channel.
Barn Doors
A term used in television production to describe
the effect that occurs when a 4:3 image is viewed on a 16:9 screen. When this
happens, viewers see black bars on the sides of the screen or "barn
doors."
Bit Rate
Bit rate is measured as "bits per
second" (bps) and refers to the rate at which the data is transmitted. For
Digital TV, the maximum possible bit rate within the bandwidth is 19.4 Mbps
while SDTV has a lower bit rate. The higher the bit rate, the more data is
processed which usually results to higher picture resolution or better sound
quality.
Burn-in
Burn-in is the result of a static image or
pattern appearing so regularly on a screen that it ages the phosphors and
remains as a ghost image.
Codec
Codec is a short term for “Coder-decoder.” This
device is used to convert analog video and audio signals into digital format,
and vice verse, it can also convert received digital signals into an analog
format.
Component Video Connection
The output of a video device (such as a DTV
set-top box), or the input of a DTV receiver or monitor consisting of three
primary color signals: red, green, and blue that together convey all necessary
picture information. With current consumer video products, the three component
signals have been translated into luminance (Y) and two color difference
signals (PP, PR), each on a separate wire.
Composite Video
An analog, encoded video signal that includes vertical
and horizontal synchronizing information. Since both luminance (brightness) and
chrominance (color) signals are encoded together, only a single connection wire
is needed. A composite video jack is usually a single RCA-type.
Compression
Compression allows the delivery of more programs
in a single channel. It is an electronic manipulation of digital data that
reduces and removes redundant and/or non-critical information in the digital
picture and sound without noticeably degrading picture quality. One of the
compression methods is called MPEG-2.
Computer Input
Some HDTV sets have an input like SVGA or VGA
that allows the TV sets to be connected to computers.
Contrast Ratio
Measures the difference between the brightest
whites and the darkest blacks a display can show. The higher the contrast
ratio, the greater the ability of a display to show subtle color details and
tolerate ambient room light. Contrast ratio is an important spec for all types
of TV display, but especially for front projectors.
CRT (Cathode-Ray Tube)
A CRT ("picture tube") is a
specialized vacuum tube in which images are created when an electron beam scans
back and forth across the back side of a phosphor-coated screen. Each time the
beam makes a pass across the screen, it lights up a horizontal line of phosphor
dots on the inside of the glass tube. By rapidly drawing hundreds of these
lines from the top to the bottom of the screen, images are created.
D/A
Conversion of digital to analog signals. The
device is also referred to as DAC (D/A converter). In order for conventional
television technology to display digitally transmitted TV data, the data must
be decoded first and then converted back to an analog signal.
Datacasting
Also known as "enhanced TV."
Datacasting is the act of providing enhanced options offered with some digital
programming to provide additional program material or non-program related
resources. This allows viewers the ability to download data (video, audio,
text, graphics, maps, services, etc.) to specially equipped computers, cache
boxes, set-top boxes, or DTV receivers.
Decoder
See "codec." A device or program that
translates encoded data into its original format (i.e., it decodes the data.)
Deinterlacing
The process of converting an interlaced-scan
video signal (where each frame is split into two sequential fields) to a
progressive-scan signal (where each frame remains whole). De-interlacers are
found in digital TVs and progressive-scan DVD players. More advanced
de-interlacers include a feature called 3-2 pulldown processing. For TVs,
de-interlacing is often referred to as "line-doubling" or
"upconversion."
Digital
Digital refers to the circuitry in which
data-carrying signals are restricted to one of two voltage levels,
corresponding to logic 1 or 0.
Digital Cable
A service provided by many cable providers,
digital cable offers viewers more channels. Contrary to many consumers'
beliefs, digital cable is not the same as High-Definition Television or digital
television; rather digital cable simply offers cable subscribers the options of
paying for more services. Digital Monitor: DTV monitors are televisions that
can display a digital signal but lack an integrated tuner (unlike an integrated
digital set), and thus cannot receive a digital broadcast signal without an
additional set-top box.
Digital Television (DTV)
Digital TV is the umbrella term encompassing
High-definition Television and several other applications, including Standard
Definition Television, datacasting, multicasting and interactivity.
Digital Tuner
A digital tuner serves as the decoder required
to receive and display digital broadcasts. It can be included inside TV sets or
via a set-top box.
Direct-view TV
The conventional and most common type of TV,
which uses a single large (up to 40") CRT to display images.
DLP (digital light processor)
A proprietary electro-mechanical device invented
by Texas Instruments that reflects light on a pixel-by-pixel basis to create a
projected image. The key components of a DLP are the digital micromirror
device, which actually stores image information and reflects light with
thousands of 16x16-micron mirrors based on that information, a scan converter
that decodes multiple signal sources into progressive red, green and blue
information and an RGB color filter wheel.
Dolby Digital (Dolby AC-3)
Dolby Digital, also called Digital 5.1 or AC-3,
is a five-channel surround sound system which delivers CD-quality digital audio
and provides five channels of full frequency for front left, front right,
center, surround left and surround right speakers, plus one channel for LFE
(low frequency effect) subwoofer. It is the official audio standard for Digital
TV and HDTV.
Downconvert
A term used to describe the format conversion
from a higher resolution input signal number to a lower display number, such as
1080i input to 480i display. Some HDTV tuners are able to downconvert digital
HDTV signals for display on a regular analog TV.
DTS
Digital Theater Systems sound. Discrete 5.1
channel surround system similar but not the same as Dolby Digital. Dolby
Digital is the DTV standard, but DTS competes with it on DVD and in the movie
theaters.
DTV (Digital Television)
DTV stands for Digital Television. It refers to
all digital television formats and standards established by the Advanced
Television Systems Committee (ATSC). Two basic DTV standards are HDTV
(high-definition television) and SDTV (standard-definition television)
DVI (Digital Visual Interface)
DVI is a standard that provides a
high-bandwidth, low-cost digital interface between a video source and a display
device. It is capable of carrying uncompressed unprotected high resolution
video transfers of HDTV signals, and supports real-time complex graphics
displays and user interfaces found in program guides andother interactive
features for high definition television.
DVI w/HDCP (Digital Visual Interface with High
Density Copy Protection)
This is the same as above adding high-density
digital copy protection, primarily for the secure transfer of high-resolution
video content.
EDTV (Enhanced-Definition Television)
EDTV stands for Enhanced Definition Television.
The picture quality of EDTV is superior to that of standard analog TV (480i)
but not as good as HDTV (1080i or 720p). EDTV displays the picture at a
resolution of 852x480 (480p) lines in either 4:3 or 16:9 aspect ratios and it
includes Dolby Digital sound system.
EPG
EPG stands for electronic program guide. It is a
system displaying channels and program data on-screen for an extended time
period (typically 36 hours or more).
Frequency
The number of times per second that a signal
fluctuates. The international unit for frequency is the hertz (Hz). One
thousand hertz equals 1 KHz (kilohertz). One million hertz equals 1 MHz (megahertz).
One billion hertz equals 1 GHz (gigahertz). Television is broadcast in
frequencies ranging from 54 MHz to 216 MHz (VHF) and 470 MHz to 806 MHz (UHF).
Flat-panel TV
Flat-panel TV typically displays picture using
gas plasma or LCD technology and is only a few inches thick.
Frame rate
The rate at which frames are displayed. The
frame rate for movies is 24 frames per second (24 fps). In regular NTSC video,
the frame rate is 30 fps. The frame rate of a progressive-scan format is twice
that of an interlaced-scan format it's at 60 fps.
Front-projection TV
Front-projection TV comprises 2 parts – a
separate front projector (usually placed on a table or ceiling-mounted) and a
reflective screen (or simply a wall). The projector is placed at one end of the
room, the screen is at the other end, and the speakers may be placed wherever
they will provide you good sound experience. The picture can be rather large
but remember – the larger the picture, the more visible the pixels or scan
lines and the darker the image.
Gain
Measures the light-reflecting ability of a
projection screen. The higher the number, the greater the amount of light
reflected back to the viewer(s).
Generation Loss
This refers to video degradation caused by
successive recordings (dubs of other dubs) from the master source. This is
overcome by digital recording.
Ghosting
Ghosting means multiple overlaid TV images or
“ghosts” which you can notice around the objects while watching TV. Ghosting is
caused by the broadcast signal traveling to your TV through various obstacles,
for example hills or tall buildings, and your antenna picks up the original TV
signal along with signals reflected by the obstacles. If the ghosting is
changing rather than static, it may be caused by the signal reflected by
flexible objects, for example trees.
Grayscale
This describes the ability of a display to be in
a state between full ON and full OFF. Each of these definable states is a “gray
level”. The grayscale is composed of the number of gray levels. The more levels
a display has the better.
HDCP (High-Bandwidth Digital Content Protection)
HDCP encryption is used with high-resolution
signals over DVI and HDMI connections and on D-Theater D-VHS recordings to
prevent unauthorized duplication of copyrighted material.
HDMI (High Definition MultiMedia Interface)
HDMI assures that the best video signal is
always sent from source (e.g., HDTV signal) to the display (e.g., plasma
television). It does this by allowing uncompressed video and multi-channel
audio data to be input to the display device through one single cable. The need
for multiple analog connections for high-resolution audio and video are
eliminated. Without a HDMI connection one would need 3 video connections for high
definition video and 6 audio connections for high-resolution audio.
HD-ready
Describes a television that is capable of
displaying one or both of the prescribed high-definition television formats
(720p, 1080i) but is not equipped with the requisite tuner/converter to receive
digital signals.
HDTV (High-Definition Television)
HDTV stands for High Definition Television. HDTV
refers to the highest-resolution formats of the 18 total DTV formats. With
twice the vertical and horizontal picture resolution, the picture of HDTV is
approximately twice as sharp as that of NTSC. HDTV has widescreen aspect ratio
of 16:9 and Dolby Digital sound system. Currently used HDTV formats - 1080i and
720p both offer reduced motion artifacts like ghosting and dot crawl.
High Def
Usually refers to the High Def Forum but can
also refer to High Defintion (see below). :)
High Definition
Usually refers to a video format consisting of
either 720 active lines of progressive video or 1080 active lines of either
progressive or interlaced video.
IEEE-1394 (also FireWire or i.LINK)
High-speed digital video and data interface
technology adopted by the
Interactive Television
This is when TV programming features interactive
content and enhancements, blending traditional TV viewing with the
interactivity of a personal computer.
Interlaced Scanning
Interlaced scanning is a method based on the
principle that the screen shows every odd line at one scan of the screen and
then all the even lines in a second scan. There are 30 frames shown per one
second and this can make larger screen flicker, which is the usual problem with
interlacing. However, LCD and plasma screens cannot display interlaced signals
and must first convert them to a progressive format and then they can display
the transmitted images.
LCD (Liquid Crystal Display)
LCD stands for Liquid Crystal Displays. LCD
technology is one of the methods used to create flat-panel TVs. The display
consists of two polarizing transparent panels and a liquid crystal solution
sandwiched in between. An electric current passed through the liquid causes the
crystals to align so that light cannot pass through them. Each crystal acts
like a shutter, either allowing light to pass through or blocking the light.
The pattern of transparent and dark crystals forms the image.
LCoS (liquid crystal on silicon)
A type of LCD and projection TV display
technology (can be used in rear-projection and front-projection TVs), LCoS
sandwiches liquid crystals between a plate of glass and a silicon microchip
rather than between two layers of glass.
Letterbox
Letterbox refers to the image of a wide-screen
picture on a standard 4:3 aspect ratio television screen, typically with black
bars above and below. It is used to maintain the original aspect ratio of the
original source (usually a theatrical motion picture of 16:9 aspect ratio or
wider).
Light output
Is the amount of light produced by a front
projector. Expressed in "lumens" or "ANSI lumens," with the
higher number indicating greater light output.
Lumen
The unit of measure for light output of a
projector.
Luminance
The brightness or black-and-white component of a
color video signal. Determines the level of picture detail.
Multicasting
The option to multicast was made possible by
digital technology to allow each digital broadcast station to split its bit
stream into 2, 3, 4 or more individual channels of programming and/or data
services. (For example, on channel 7, you could watch 7-1, 7-2, 7-3 or 7-4.)
Native Resolution
Native resolution is the actual number of plasma
cells that can be illuminated at once, and it's the very first thing you should
check when shopping for a plasma display. In order to enjoy high-definition
programming, your TV must have a minimum native resolution of 720p. (Pioneer
PureVision plasmas actually exceed high-definition standards with 768p native
resolution.)
NTSC (National Television Systems Committee)
NTSC or National Television System Committee is
the organization that develops technical standards for black-and-white television
and color television. NTSC established the 525-line (480 visible) analog
broadcast TV standard. The new DTV digital broadcast standard will eventually
replace NTSC.
Over-the-air Broadcast (OTA)
Over-the-air Broadcast is also called
Terrestrial Broadcast. It is standard over-the-air broadcast to an antenna, as
opposed to satellite or cable transmission.
Picture-in-picture (PIP)
Picture-in-picture is a television feature in
which you can see one program inside a small window on the screen, while
watching another program on the large background screen. You can choose
whatever you wish – you can watch two TV programs simultaneously or you can
watch TV and video or DVD at the same time.
Pixel
Short for "picture element." The
smallest bit of data in a video image. The smaller the size of the pixels in an
image, the greater the resolution.
Plasma Displays (PDP)
Plasma display is created by thousands of tiny
tubes filled by ionized gas in a plasma state.
Progressive Scanning
Progressive scanning is used by some HDTVs.
Progressive scanning offers rather smooth picture as 720 or 1080 horizontal
lines are scanned progressively or in succession in a vertical frame that is
repeated 30 times a second. Some displays, for example LCD and plasma use
progressive scanning method, while CRTs may use progressive (e.g. in computer
monitors) or interlaced scanning method.
Rear Projection
Rear projection is a TV system where the picture
is projected against a mirror inside the cabinet and you can watch it as you
would an average television. Until recently, the rear projection TVs comprised
three CRTs but the new types of rear projection TVs include LCD.
Refresh Rate
The refresh rate for a monitor is measured in
hertz (Hz) and is also called the vertical frequency, vertical scan rate, frame
rate or vertical refresh rate. The old standard for monitor refresh rates was
60Hz, but a new standard developed by VESA sets the refresh rate at 75Hz for
monitors displaying resolutions of 640x480 or greater. This means that the
monitor redraws the display 75 times per second. The faster the refresh rate,
the less the monitor flickers.
Resolution
Resolution reflects the density of lines, and
dots per line which make up a visual image. It is measured by the number of
pixels displayed. The level of resolution directly affects picture quality.
Usually the higher number of lines and dots means also sharper and more
detailed picture. Analog TV has a little over 200,000 color pixels while HDTV,
with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million
pixels creating the image.
Sampling
This is the digital process by which analog
information is measured, often millions of times per second, in order to
convert analog to digital.
SDTV (Standard-Definition Television)
SDTV stands for Standard Definition Television.
The SDTV picture, having either in 4:3 or 16:9 aspect ratios, is better and of
higher quality than the one of NTSC, however, it does not reach the quality and
resolution of HDTV. SDTV is based on 480 lines of vertical resolution and in
both interlaced and progressively scanned formats.
Set-top Box (STB)
Also called converter boxes, these receivers
convert broadcasts (either analog cable, digital cable, or HDTV) for display on
a television. HDTV-ready TVs (those without a built-in HDTV tuner) must be
connected to a compatible HDTV tuner set-top box in order to receive digital
television programs.
SVGA
This acronym is short for the "Super Video
Graphics Array" display mode. SVGA resolution is 800 x 600 pixels.
S-Video
Separated video. An encoded video signal which
separates the brightness from color data. S-video can greatly improve the
picture when connecting TVs to any high quality video source such as digital
broadcast satellite (DBS) and DVDs.
UHF
Ultra high frequency, the range used by TV
channels 14 through 69.
Upconverting
Process by which a standard definition picture
is changed to a simulated high-definition picture.
VGA
This acronym is short for the "Video
Graphics Array" display mode. VGA resolution is 640 x 480 pixels.
VHF
Very high frequency, the range used by TV
channels 2 through 13.
Widescreen
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Nikon D300
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SDR-H40 Hard Drive Camcorder
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LT-52244 52" LCD Television
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HV30 Vixia Camcorder
