Glossary of Terms
Glossary of Terms
Select a letter or number to browse the glossary
Aspect ratio of 16 units wide by 9 units high is a wider format than the
current 4x3 TV standard. This is the standard aspect ratio for widescreen
TVs and HDTV. Can also be described as a 1.78 aspect ratio, i.e. width
is 1.78 times height. Also referred to as 16/9 and 16:9.
Aspect ratio of 4 units wide by 3 units high is the current standard for
TVs in the United States. Can also be described as 1.33 aspect ratio.
Also referred to as 4/3 and 4:3.
Analog to digital conversion.
The inherent resolution of a display device (plasma screen, television,
projector or monitor) which enables pixels to be individually addressed.
The device, however, may not be capable of displaying this resolution.
An artifact produced by distorting or not using the high frequency components
of an image, signal, data stream, etc. due to some limitation such as
undersampling or inadequate detection bandwidth. The result is unwanted
appearance of low frequency components (aliases) which must be filtered
out and replaced with the missing high frequency components. The process
of removal/replacement of frequencies is called "anti-aliasing".
A form of data transmission using a continuously variable signal, in contrast
to digital transmission, which uses discrete numerical steps.
"Standard" television broadcasts analog TV. Analog signals vary continuously,
representing fluctuations in color and brightness. NTSC is an analog system.
A process of storing images with different horizontal and vertical magnifications
for later display through a reversed procedure. Generally, the image is
squeezed inward from the sides in relation to the height. So, if the original
picture is of a circle, then the anamorphic processing would produce a
tall, thin oval. On receiving the signal, some device will readjust these
different horizontal and vertical magnifications back to normal. The anamorphic
process has the advantage of enabling wide aspect ratio pictures to be
stored on a recording medium originally designed for the 4x3 aspect ratio.
Specifically, an anamorphic DVD stores a high quality widescreen movie
for viewing on widescreen TVs.
A unit that indicates lumen brightness of projectors. ANSI (American National
Standards Institute) has established the standard for measurement of lumen
brightness. For example, if one projector uses Halogen lamps and another
metal-halide, the halogen projector will seem noticeably dimmer even if
the two units rate the same.
In electronic communication, the term refers to the adding of additional
images or parts of images so as to convince the eye that it sees something
that cannot be represented digitally. The goal is usually to make curved
or diagonal lines appear smooth, or to show straight horizontal or vertical
lines in certain positions. Lines cannot be represented smoothly or in
the proper position because the display device resolution is not sufficient
to represent the image accurately. In practice, the eye is fooled into
completing the edge between the background and foreground colors.
Unwanted visible effects in a picture created by disturbances in the transmission
or image processing, for example "edge crawl" or "hanging dots" in analog
pictures, or "pixelation" in digital images.
The aspect ratio of a display screen is described by the width x height,
for example 4x3 means 4 units wide by 3 units high. Current U.S. TV broadcasts
use a 4:3(1.33:1) aspect ratio. Digital TV is broadcast with a 16:9 (1.78:1)
ratio, and most feature films are shot in the ratio range of 1.85:1 up
The Advanced Television Systems Committee Inc., is an international, non-profit
organization developing voluntary standards for digital television. The
ATSC member organizations represent the broadcast, broadcast equipment,
motion picture, consumer electronics, computer, cable, satellite, and
semiconductor industries. The most common formats are 480p (525 scan lines,
480 of them active, per frame progressive scan, each scan line divided
into 640 or 704 parts or pixels, 720p which is 720 active scan lines each
with 1280 pixels, and 1080i (1080 active scan lines as two 540 scan line
interlaced fields, 1920 pixels on a line).
The Advanced Television Technology Center is a private, non-profit corporation
organized by members of the television broadcasting and consumer products
industries to test and recommend solutions for delivery and reception
of a new U.S. terrestrial transmission system for digital television (DTV)
service, including high definition television (HDTV). The Technology Center
operates a state-of-the-art laboratory facility that supports the needs
of the U.S. television industry and private standards-setting bodies.
Its primary activity is to facilitate implementation of digital television.
A range of frequencies used for transmitting information such as images
and sound. For U.S. television broadcasters, the Federal Communications
Commission (FCC) has allocated 6MHz for each channel. For DTV, the maximum
bit rate possible within the bandwidth is 19.4 Mbps, which is used by
one HDTV channel. SDTV has a lower bit rate, therefore the same bandwidth
can accommodate more than one channel.
Blu-Ray, also known as Blu-ray Disc (BD) is one of the next generation
optical disc formats, developed by the Blu-ray Disc Association (BDA),
a group of leading consumer electronics and PC companies (including Apple,
Dell, Hitachi, HP, JVC, LG, Mitsubishi, Panasonic, Pioneer, Philips, Samsung,
Sharp, Sony, TDK and Thomson).The new format is designed to replace the
existing DVD technology, and allows recording, rewriting and playback
of high-definition video (HD), as well as storing large amounts of data.
A single layer Blu-ray Disc can hold 25GB, which can be used to record
over 2 hours of HDTV, or more than 13 hours of standard definition TV.
Dual layer versions can hold 50GB, and versions with more layers are planned.
While the current DVD technologies use red laser to read and write data,
the new format uses blue-violet laser, hence the name, Blu-ray. In spite
of the different types of laser used, the new Blu-ray products can easily
be made backwards compatible, allowing playback of existing CDs and DVDs.
The advantage of the blue laser is that the shorter wavelength allows
for more precise focus, and therefore it becomes possible to pack data
more tightly on the same size disc.
The following formats are part of the Blu-ray Disc specification:
BD-ROM - read-only format for software, games and movie distribution.
BD-R - recordable format for HDTV recording and PC data storage.
BD-RE - rewritable format for HDTV recording and PC data storage.
Blu-ray is one of the emerging technologies expected to replace VCRs and
DVD recorders over the coming years, with the transition to HDTV. One
of these formats will become the new standard for PC data storage and
HD movies in the future.
See also HD-DVD.
A connector that has a bayonet-type shell with two small knobs on the
female connector which lock into spiral slots in the male connector when
it is twisted on. This connection is preferred by professionals because
of its perfect 75ohm impedance and positive locking connection. Different
sources expand BNC as Bayonet Navy Connector, British Naval Connector,
Bayonet Neill Concelman, or Bayonet Nut Connection.
The Consumer Electronics Association (CEA) membership unites more than
1700 companies within the U.S. consumer technology industry. Member-only
resources include: exclusive information and unparalleled market research,
networking opportunities with business advocates and leaders, up-to-date
educational programs and technical training, exposure in extensive promotional
programs, and representation from the voice of the industry, CEA, promoting
and advancing member needs and interests.
The Custom Electronic Design & Installation Association (CEDIA), is a
global trade association of companies that specialize in planning and
installing electronic systems for the home. These systems include home
networking, home automation and communication systems, media rooms, single
or multi-room entertainment systems, and integrated whole-house subsystems
providing control of lighting, security and HVAC systems. The association
was founded in September 1989 and has a total membership of more than
3,000 member companies. The Cedia Expo Show is held annually in September.
The Consumer Electronics Show is an annual convention held in Las Vegas
each January that promotes the industry and its products.
The color information contained in a video signal.
Slight horizontal shifting of color relative to the luminance details
of the picture giving the appearance of a poorly done child's coloring
book. It can result from less than perfect circuitry or cables where the
color subsignals take a longer or shorter time to arrive at the display
Chroma Upsampling Error
Also referred to as the chroma bug, this error occurs because most digital
video has every two scan lines sharing the same coloration. The bug manifests
itself as thin black horizontal strips occurring every other line, or
alternating between two colors near edges of sharply contrasted color
objects. A good place to spot this artifact is in the Toy Story main menu
(the blue text).
A standard cable used for many video connections, consisting of a central
inner conductor, wrapped in a cylindrical outer conductor.
An electronic filter that is used to separate luminance and color information
from an input composite video signal. (Color and luminance must subsequently
be recombined in a different way, namely isolate red, green, and blue
content,ÿto produce the picture.) Comb filters are used in the medium
grade to more expensive TV sets to perform the necessary task of separating
the two.ÿNotch and bandpass filters, common on lower priced TV sets as
an alternative, produce acceptable pictures but with more discoloration
and limited horizontal resolution.
The output of a video device (such as a DTV set-top box or DVD player),
may be transmitted in component video format, or the input of a DTV receiver
or monitor consisting of the 3 component signals: luminance or brightness
(Y) and two color difference signals (PB, PR), each on a separate wire.
An analog, encoded video signal (such as NTSC) 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 signal is typically carried on a single cable
with a yellow red connection at each end.
A method of electronically reducing the number of bits required to store
or transmit data within a specified time or space. The video industry
uses several types of compression methods but the method adopted for DTV
and DVD is called MPEG2.
In general, almost all computer monitors will work with the iScan. The
only requirement is that the monitor be capable of being used at a VGA
resolution (640x480) at 60Hz (frames per second). Since this is currently
the lowest common denominator for computer monitors, only very old monitors
may not be compatible. The biggest drawback to using a computer monitor
as a television is that they are typically not as bright as televisions.
In addition, with computer monitors, you won't have access to all of the
fancy Picture-in-Picture, stereo audio and other features typically found
in today's TVs.
A Cathode Ray Tube is one of the main components of monitors and TVs.
A beam of electrons is shot towards the CRT and as they collide with phosphors
on the inside surface, they produce light. Newer technologies are now
available, such as LCD panels and projection units which are not so heavy
or bulky as the old CRT monitors and TVs. As CRTs are phosphor based,
they are susceptible to differential aging of the phosphors, commonly
referred to as image retention or burn-in.
Digital to analog conversion.
DBS (Digital Broadcast Satellite)
Digital format for music and video that beams high-powered signals across
North America from satellites orbiting above the equator to satellite
dishes providing a wide range of programming in a high-quality digital
format. Direct broadcast satellites are positioned above the equator in
geostationary orbit, meaning that the satellite orbits at the same speed
as the spin of the earth, so is always facing the same part of the globe.
The satellites beam down a high-powered signal in a broad spectrum of
radio frequencies. The small 18 inch satellite dishes receive the signal
and transfer it to a decoder box in the home. The decoder box then decodes
the digital data and supplies an analog video and audio signal to the
video display and audio system. The digital video and audio feed from
a direct broadcast satellite is encoded with MPEG-2 compression.
Deinterlacing is the complex process that converts a traditional interlaced
video source into the progressive scan format required by modern high
definition displays. However, not all deinterlacing processors are equal,
and some of the other interlacers on the market will leave you looking
at noisy artifacts and motion blurs. Not ours! DVDO technology delivers
state-of-the-art progressive-scan video for the best possible picture
from interlaced video sources enabling flawless, seamless, source-adaptive
and motion-adaptive deinterlacing.
Expressed or represented by a series of numbers. For example, a digital
signal is expressed by the numerical value of the signal size at regular
points in time. Sounds and pictures can be recorded, stored, and played
back digitally with no distinguishable difference from the original if
the time interval between samples is sufficiently small.
A video image converted into pixels. The numeric value of each pixel can
be stored in a computer memory for subsequent processing and analysis.
In the U.S., this term is commonly used to refer to a TV set that can
display HDTV broadcasts. Actually many HDTV sets use analog processing
for HDTV, they have no HDTV tuner built in and the HDTV video signal fed
from an external tuner has been fully decoded and converted to analog.
On the other hand, the best display of analog broadcasts requires digital
components, namely the comb filter and a de-interlacer and/or scaler.
Direct View Television
Direct View is the formal name for a normal "tube" TV. They are based
on large CRTs (cathode ray tubes) that project the image onto a the surface
of a phosphor-lined glass screen which you view directly, hence the name.
Some other devices, such as projectors may also use CRTs but they project
the image onto a separate screen. Direct View sets, if they are capable
of accepting a 31.5kHz progressive signal, are typically much improved
with a DVDO iScan. Some of these sets may have their own internal line
doubler or "upconverter" which is used to convert the incoming 15.75kHz
(normal) signal to 31.5kHz (or higher). The advantage of the DVDO iScan
in these cases is that it does a much better job of this upconversion
than any of the current generation of embedded line doublers.
At the heart of every Digital Light Processing projection system is an
optical semiconductor known as the Digital Micromirror Device, or DMD
chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in
1987. The DMD chip is probably the world's most sophisticated light switch.
It contains a rectangular array of up to 2 million hinge-mounted microscopic
mirrors; each of these micromirrors measures less than one-fifth the width
of a human hair. When a DMD chip is coordinated with a digital video or
graphic signal, a light source, and a projection lens, its mirrors can
reflect an all-digital image onto a screen or other surface. The DMD and
the sophisticated electronics that surround it are what we call Digital
Light Processing technology.
The (center to center) spacing between phosphor dots or stripes of the
same color on a display screen. The smaller the better for picture sharpness,
0.28 mm is considered the minimum acceptable for a good computer display,
while a typical 20" TV has an 0.81 mm dot pitch and large screen TV's
have larger dot pitches. Many TV screens use vertical stripes rather than
dots in which case the dot pitch applies only in the horizontal direction.
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
Refers to standard or high definition TV whose signals are digital during
production, transmission, storage, and reception. DTV has many advantages.
It can be compressed to provide four, five or more channels in the same
bandwidth required for one channel of NTSC television (the current U.S.
standard). Digital television provides a crystal clear, "snow-free" picture
to all TVs that can receive a minimum level signal. Within the DTV or
ATSC (Advanced Television Systems Committee) standard, there are 18 current
formats, several of which are called HDTV. Broadcasters will have the
option of showing several SDTV programs or one or two HDTV programs, all
with a single DTV channel. Note: Even digital TV signals are converted
to analog to pass through component video or S-video cables and/or just
before being displayed on a picture tube. The fewer analog/digital conversions
there are altogether, the better the overall quality can be.
The Digital Video Disc or Digital Versatile Disc, is similar to a CD-ROM
except that it stores up to 12 times as much data. DVD is the successor
to CD-ROM technology. DVD discs are the same size physically as CD-ROM
discs, but hold between 4.7 - 18 GB of data. Initial DVD drives were read-only
devices, but newer versions work with rewriteable media.
Digital Visual Interface (DVI) is a type of cable and connection created
in 1999 by the Digital Display Working Group (DDWG), which is a cooperative
of technology companies including Silicon Image, Intel, Compaq, Fujitsu,
HP, IBM and NEC. The DVI 1.0 standard was originally created to enable
digital-to-digital, high bandwidth data transfer between a computer and
a flat screen monitor. However, because of DVIs ability to also process
high-bandwidth HDTV video, interest was generated in the consumer electronics
industry. DVI is the fastest way to transfer data or video. Using DVI
with a digital display device, such as a projector or flat screen monitor,
will create an entirely digital-to-digital connection, providing the consumer
with the best quality image.
DVI 1.0 specification
DVI-D: Digital Only
DVI-I: Digital and Analog
DVI-A: Analog Only
Dual Link: Dual Link DVI supports 2x165 MHz (2048x1536 at 60 Hz, 1920x1080
at 85 Hz). A dual link implementation utilizes all 24 of the available
Single Link: Single Link DVI supports a maximum bandwidth of 165 MHz (1920x1080
at 60 Hz, 1280x1024 at 85Hz). A single link implementation utilizes 12
of the 24 available pins.
The European Broadcasting Union (EBU) is the largest professional association
of national broadcasters in the world. The Union has 72 active Members
in 52 countries of Europe, North Africa and the Middle East, and 50 associate
Members in 30 countries further afield. The EBU was founded in February
1950 by western European radio and television broadcasters. It merged
with the OIRT - its counterpart in Eastern Europe - in 1993. The Union
is in the forefront of research and development of new broadcast media,
and has led or contributed to the development of many new radio and TV
systems: radio data system (RDS), digital audio broadcasting (DAB), digital
television (DVB), high- definition TV (HDTV). At its office in Brussels,
the EBU represents the interests of public service broadcasters before
the European institutions.
Enhanced definition is a signal that is either 480p (NTSC) or 576p (PAL)
that can be either 4:3 or 16:9. Fox has broadcast shows like 24 in EDTV
with a 16:9 ratio.
Extended Display Identification Data is a VESA standard data format that
contains basic information about a monitor and its capabilities, including
vendor information, maximum image size, color characteristics, factory
pre-set timings, frequency range limits, and character strings for the
monitor name and serial number. The information is stored in the display
and is used to communicate with the system through a Display Data Channel
(DDC), which sites between the monitor and the PC graphics adapter. The
system uses this information for configuration purposes, so the monitor
and system can work together.
The Federal Communications Commission (FCC) is an independent United States
government agency, directly responsible to Congress. The FCC was established
by the Communications Act of 1934 and is charged with regulating interstate
and international communications by radio, television, wire, satellite
and cable. The FCC's jurisdiction covers the 50 states, the District of
Columbia, and U.S. possessions.
Half of an interlaced video frame containing either all the odd or all
the even numbered horizontal lines. The frame is the entire image consisting
of two fields. An interlaced image such as the NTSC analog television
standard draws all the odd lines of an image followed by all the even
lines of an image (first drawing lines 1, 3, 5, 7, and so on then coming
back to draw lines 2, 4, 6, 8, and so on). A field consists of all the
odd or even lines that combine to create a complete image.
A type of cabling technology for transferring data to and from digital
devices at high speed. Some professional digital cameras and memory card
readers connect to the computer over FireWire. FireWire card readers are
typically faster than those that connect via USB. Also known as IEEE 1394.
Fixed Pixel Display (FPD)
An all encompassing term for technologies that have pixels rather than
scan lines like a CRT. LCD, DLP, plasma and LCoS are popular technologies
that are used in fixed pixel displays.
Flat Panel Display (also known as FPD)
A type of display that is much thinner compared with standard CRT based
displays. Plasma and LCD screens are both types of FPDs.
A type of picture tube, based on CRT technology, which has front glass
which is flat rather than the typical curved surfaced. Not to be confused
with flat panel displays.
One complete screen in a video image. A single frame is related to a single
picture or a single photograph. By combining multiple frames in rapid
succession, the illusion of motion is created. In the movies, 24 frames
pass by every second. On television, there are 30 frames displayed each
Frames Per Second (FPS)
A measure of the number of pictures (or frames) that are displayed per
second to create a moving image. For TV, this is typically between 50
and 60 FPS.
Gas Plasma Display
A type of monitor technology typically used to create large monitors that
are only a few inches thick. The technology works by creating a matrix
of red, green and blue pixels from plasma bubbles that are turned on or
off by selectively powering them.
HD-DVD, also known as Advanced Optical Disc (AOD) is one of the next generation
optical disc formats, developed by Toshiba and NEC. The new format is
designed to replace the existing DVD technology, and allows recording,
rewriting and playback of high-definition video (HD), as well as storing
large amounts of data. The new high-definition movies, which have a much
clearer image, require up to 5 times as much storage space. A single layer
HD-DVD can hold 20GB which is just over 1 hour of high-definition video,
or 6 hours of standard definition video. A dual layer version can hold
While the current DVD technologies use red laser to read and write data,
the new format uses blue-violet laser. The advantage of the blue laser
is that the shorter wavelength allows for more precise focus, and therefore
it becomes possible to pack data more tightly on the same size disc.
There are three versions in development:
HD DVD-ROM discs are pre-recorded and offer 15 GB per layer per side,
offering up to 30 GB per side or 60 GB per disc. These can be used for
distributing HD movies.
HD DVD-RW discs are re-writable and can be used to record 20 GB per side
for re-writable versions.
HD DVD-R discs are write-once recordable discs with a capacity of 15 GB
HD-DVD is one of the emerging technologies expected to replace VCRs and
DVD recorders over the coming years, with the transition to HDTV. One
of these formats will become the new standard for PC data storage and
HD movies in the future.
See also Blu-ray
HDCP (High-Bandwidth Digital Content Protection)
A standard, developed by Intel, that protects digital video and audio
signals transmitted over DVI or HDMI connections between two HDCP-enabled
devices. The nature of a digital signal makes it possible to create perfect
copies of the original signal an unlimited number of times without degradation,
something that is impossible with an analog signal. So, in order to protect
copyright holders (movie studios, etc.) from having their programs copied
and shared, the HDCP standard provides for the secure, encrypted transmission
of digital signals.
HDCP only functions across DVI or HDMI connections between two HDCP capable
devices. The source device (such as a DVD player or HDTV tuner) encrypts
the digital signal using the HDCP standard, then sends that signal over
the DVI or HDMI connection to the receiving device (HDTV, etc.). The receiving
device decodes the signal using HDCP and uses the signal as it is allowed.
If one of your devices is HDCP compliant, but the other is not, then you
cannot connect them using DVI or HDMI - you will get an error. However,
you can still use the analog signal from the source device (eg: component
video signal, S-video signal). HDCP does not apply to analog signals.
The FCC approved HDCP as a "Digital Output Protection Technology" on August
4th, 2004. FCC regulations will require digital output protection technologies
on all digital outputs from HDTV signal demodulators as of July 1st, 2005.
High Definition Multimedia Interface is the first industry-supported,
uncompressed, all-digital audio/video interface. Based on the earlier
DVI (video only) standard, HDMI provides an interface between any audio/video
source, such as a set-top box, DVD player, and A/V receiver and an audio
and/or video monitor, such as a digital television (DTV). HDMI supports
standard, enhanced, or high-definition video, plus multi-channel digital
audio on a single cable. It transmits all ATSC HDTV standards and supports
8-channel digital audio, with bandwidth to spare to accommodate future
enhancements. HDMI will offer 'legacy' support of older DVI connections.
The new High-definition television standard displays and broadcasts signals
that use many more scan lines than normal television and a 16x9 aspect
ratio rather than the old 4x3 aspect ratio of a standard TV set. HDTV
also refers to the televisions that pick up these signals. Japan first
used an analog form of HDTV. The United States, and now Japan use a digital
form of HDTV, or DTV. HDTV does not degrade through many generations of
editing, which means he final broadcast is crystal clear. The resulting
picture is up to five times sharper than that of today's sets, with CD-quality
sound. HDTV offers reduced artifacts (i.e. ghosting, dot crawl), and provides
5.1 independent channels of CD-quality stereo surround sound, (also referred
to as dolby digital).
An analog TV signal in the U.S. has 525 scan lines for the image, and
each image is refreshed every 30th of a second (half of the scan lines
are painted every 60th of a second in what is called an interlaced display).
480 of 525 scan lines are used to hold the picture. We can also call it
480i. The formats used in HDTV are as follows:
- 480i - 640 x 480 pixels interlaced
- 480p - 640 x 480 pixels progressive
- 720p - 1280 x 720 pixels progressive
1080p - 1920 x 1080 pixels progressive
A measure of the quality of a displayed image, relating to the number
of vertical lines, or individual picture elements across the screen from
left to right. The greater the number of vertical lines (or picture elements
across the screen), the greater the resolution. Higher resolutions result
in images which are better defined and complete. There are two primary
HDTV standards, 1080i and 720p. With 1080i the resolution is set at 1920
pixels across (horizontal resolution) and 1080 pixels top to bottom (vertical
resolution). The 720p standard provides for 1280 pixels across (horizontal
resolution) and 720 top to bottom (vertical resolution).
Horizontal Scan Rate
The number of horizontal lines of information a video display can paint
on to a screen in one second, given in hertz (Hz - cycles per second).
The horizontal scan rate of analog NTSC video is 15,750 Hz, which, at
a refresh rate of 60 screens per second gives 262.5 as the maximum number
of lines that can be displayed (vertical resolution). In a similar way,
a graphics projector with a horizontal scan rate of 63,000 Hz has a vertical
resolution of 1,050, and a data grade projector (31,500 Hz horizontal
scan rate) can furnish 525 horizontal lines.
The Institute of Electrical and Electronics Engineers specification 1394
(IEEE 1394 also called FireWire and iLink) is the transmission standard
and connector found on many consumer electronics products, including camcorders,
DTVs, set-top boxes, A/V receivers, and some DVD players. Most signals
sent over IEEE 1394 are compressed, which means they can be recorded.
For television display, interlaced scanning refers to the process of transmitting
and re-assembling a single picture frame from two passes of the image.
First the odd lines (1,3,5,...) are transmitted together, and displayed
on screen. Next, the even lines (2,4,6,...) for the same frame are transmitted
and displayed. The entire frame is displayed in two passes, or scans,
each taking 1/60th of a second. The human eye sees it as a single picture,
however, because of the persistence of the CRT phosphor. Interlaced video
was originally invented to reduce flicker given that video technology
of the time could not draw video frames fast enough to keep the top of
the picture from fading before the bottom of the picture was completed.
See also Progressive Scan.
Small, rapid varitaions in waveform or image due most often to mechanical
JPEG (Joint Photographic Experts Group)
JPEG is a digital compression standard for still video images that allows
the image to occupy less memory or disk space.
A Liquid Crystal Display Panel uses liquid crystal sandwiched between
two layers of specially treated glass. When an electrical current is sent
through the treated glass, it changes the phase of the liquid, resulting
in a color change.
LCos could be considered a hybrid between LCD and DLP. LCD uses liquid
crystals, one for each pixel, on glass panels. Light passes through these
LCD panels on the way to the lens and is modulated by the liquid crystals
as it passes. Thus it is a "transmissive" technology. On the other hand,
DLP uses tiny mirrors, one for each pixel, to reflect light. DLP modulates
the image by tilting the mirrors either into or away from the lens path.
It is therefore a "reflective" technology. LCOS combines these two ideas.
It is a reflective technology that uses liquid crystals instead of individual
mirrors. In LCOS, liquid crystals are applied to a reflective mirror substrate.
As the liquid crystals open and close, the light is either reflected from
the mirror below, or blocked. This modulates the light and creates the
image. LCOS-based projectors typically use three LCOS chips, one each
to modulate light in the red, green, and blue channels. In this it is
similar to an LCD projector which uses three LCD panels. Both LCOS and
LCD projectors deliver the red, green, and blue components of the light
to the screen simultaneously. There is no spinning color wheel used in
these projectors as there is in single-chip DLP projectors.
One of the formats used to display pictures recorded at a wider aspect
ratio than the display device permits. In letterbox format, the full image
is displayed at the original aspect ratio, with the rest of the screen
filled in with black (at the top and bottom).
Digital video processor that enhances the picture quality of a video image
by combining the two interlaced fields (all the odd lines followed by
all the even lines) to produce a single progressive scan frame of the
image. Each doubled field is then a complete frame that is projected 60
times per second. Line Doublers must also contain complex processing circuitry
to compensate for the shortcomings of the incoming interlaced video, and
the mismatches that could be created by combining the two fields. The
result is an image with much greater detail and clarity than the original
interlaced video source.
A method of converting an interlaced picture into a progressively scanned
picture. Special circuits combine the odd and even lines, then scan all
525 lines in 1/30th of a second. The result is improved detail enhancement
from an interlaced source. High quality de-interlacers use techiques more
complicated than just delivering each scan line twice.
Lip Sync. Error
A situation in motion pictures when the picture and sound do not match
in time. The sound or the picture has been delayed, so, for example, the
lips do not move in time to the speech.
A standard for measuring light output, used for comparing projectors.
However, the rating does not always match the perceived brightness. For
example, if one projector uses Halogen lamps and another metal-halide,
the halogen projector will seem noticeably dimmer even if the two units
rate the same.
Macrovision, Inc has developed an anti-taping process for video systems
that output analog NTSC, PAL, RGB or YUV video. The video source may be
from DVD, VCR, or set top box. Whether or not the anti-taping process
is present on the video outputs is determined by the source. Macrovision
works due to the differences in the way VCRs and televisions operate.
The automatic gain control (AGC) circuits within a television are designed
to respond slowly to change; those for a VCR are designed to respond quickly
to change. The Macrovision technique attempts to take advantage of this
by modifying the video signal so that a television will still display
it properly, yet a VCR will not record a viewable picture. DVD players
typically have Macrovision circuits built in to make copying of DVD movies
A distracting wavy effect produced when converging lines in a video image
are nearly parallel to a monitor's scanning lines.
A processing strategy of de-interlacing line doublers and comb filters
whose optimizing formula varies, depending on whether the subject matter
depicted was stationary/steady or moving/changing. The best devices may
vary their processing dozens of times within a single scan line.ÿThe device
must digitize several video fields, save them on a rolling basis, and
compare the content in small groups of pixels to determine whether subject
matter was moving or not.
High-quality audio/video compression format developed by the Motion Picture
Experts Group using perceptual coding and predictive technologies similar
to MPEG-1 but including a higher bit-rate and more control over the compression
and technology. MPEG-2 features a bit-rate of 3.5 to 10 megabits per second
as opposed to MPEG-1s 1.5 megabits per second. The MPEG-2 format can
be used to provide very high-quality images and is used with DVD, DBS
(direct broadcast satellite) and HDTV (in a modified high-resolution format).
MPEG-4 was defined by the Moving Picture Experts Group (MPEG) and is designed
to deliver DVD (MPEG-2) quality video at lower data rates and smaller
file sizes. Like MPEG-1 and MPEG-2 previously did for CD-ROMs and DVDs,
MPEG-4 promises to create interoperability for video delivered over the
Internet and other distribution channels. MPEG-4 will play back on many
different devices, from satellite television to wireless devices.
The National Association of Broadcasters represents the radio and television
industries in Washington -- before Congress, the FCC and federal agencies,
the courts, and on the expanding international front. NAB provides leadership
and resources to their supporting members, to broadcasters at-large, and
through ongoing public campaigns to the American people.
All fixed-pixel TVs, including every flat-panel LCD and plasma, as well
as rear-projection DLP and LCD TVs, have a certain number of pixels, known
as the native resolution, that they use to create the picture. Most widescreen
DLPs have a native resolution of 1280 x720 as an example.
National Television Standards Committee The organization responsible for
setting the standard for broadcast and reception of television signals
in the United States. The original NTSC standards were defined in 1953,
and set 525 horizontal lines of resolution, interlaced scanning and a
60Hz refresh rate. It combines blue, red, and green signals with an FM
frequency for audio. The new HDTV standard will replace NTSC over the
next few years.
TOSLINK is a standardized optical fiber connection system for consumer
audio equipment, which carries digital audio streams between components
such as DVD players and satellite receivers.
On Screen Display is a menu displayed on the screen with different options
to help users easily adjust the display's picture.
Overscan results in only part of the viewable image being shown on the
TV or display. It's deliberately done by TV manufacturers to avoid any
messy artifacts at the edges due to picture quality or an inferior power
supply. But the result is that you may be missing a significant part (up
to 15%) of the real picture.
The television standard for signal processing and broadcasting used throughout
the majority of Western Europe (except France where SECAM is the standard),
South America, Asia, and Oceania. The PAL standard broadcasts 625 lines
of resolution, nearly 20 percent more than the U.S. NTSC standard that
uses 525 lines, but at only 50 fields/second versus NTSC's 60. PAL, SECAM
and NTSC are not interchangeable with each other.
Refers to the color component video signals B-Y and R-Y respectively with
optimization for analog component video purposes or transmission.
A single dot or group of three dots (red, green and blue) on a display.
Total display pixels are usually expressed in horizontal x vertical dimension
Plasma Display Panel (PDP)
Plasma Display Panel technology is based on the same principle as the
fluorescent light, using thousands of sealed, low pressure glass chambers
filled with a mixture of noble gasses. Behind these chambers are colored
phosphors, one each of red, blue, and green for each chamber. When energized,
the chambers of plasma emit invisible UV light, which then strikes the
red, green and blue phosphors on the back glass of the display making
them produce visible light.
Most computer monitors, and some high-definition TV sets use progressive
scan, as opposed to the NTSC standard of interlaced. In progressive scanning,
all the horizontal scan lines for a single frame are painted on the screen
from top to bottom in a single pass. DTV formats usually include both
interlaced and progressive display methods.
Progressive or non-interlaced video produces a higher quality image. Interlaced
video suffers from flicker problems due to the full image not being displayed
and from alignment problems where the odd lines do not exactly line up
with the even lines. Such alignment problems can be particularly bad in
video containing fast moving images.
Projectors fall into two categories, those that project the image onto
the front (viewed) surface of a reflective screen and those that project
onto the rear surface of a translucent screen. Both types can be based
on CRTs, LCDs (liquid crystal displays), DMDs (digital micromirror device
from Texas Instruments, also known as DLP) or some other technology. Of
all of these, CRTs are the most improved with a line doubler. The effect
on LCD and DMD projectors greatly depends on the make and model of the
projector - with some there is a dramatic improvement, with others it
is not as dramatic.
Pulldown (3-2 Pulldown)
One method of committing a 24 frame per second movie on film to 60 field
per second or 60 frame per second video. Every other film frame is scanned
three times and the intervening frames scanned twice to obtain video fields
or frames. If you single step through a VCR recording of a movie, you
will often see the three-two-three-two pattern.
(RCA Plug, RCA Jack) Used for Composite Video signal interface, and Audio
signal interface (R and L separate in stereo).
Projecting an image through a translucent screen material with a special
coating which allows an image to be projected through the screen, rather
than onto the surface of the screen, for viewing from the opposite side.
As opposed to front projection. The slide or film must be reversed, or
a mirror must be used to correct the image for rear screen presentation.
In some video or computer projectors, the image can be reversed electronically.
A device that captures an over the air broadcast, satellite, cable or
microwave transmission, and presents it for listening, data processing,
The vertical scan rate of a video display, or the number of times a second
that a video display can paint an entire screen with a video signal. The
standard refresh rate in the U.S. for video (television, DVD, VHS, laserdisc)
is 60 Hz. The maximum vertical resolution of a video display can be determined
by dividing the horizontal scan rate by the refresh rate.
The density of lines and dots per line which make up a visual image. Usually,
the higher the numbers, the sharper and more detailed the picture will
be. In terms of DTV, maximum resolution refers to the number of horizontal
scanning lines multiplied by the total number of pixels per line, called
- VGA (Video Graphic Array) : 640 pixels x 480 pixels
- SVGA (Super
VGA) : 800 pixels x 600 pixels
- XGA (eXtended GA) : 1024 pixels x 768
- SXGA (Super XGA) : 1280 pixels x 1024 pixels
A serial communications interface between an electronic device and PC.
The interface can be used for remote mouse control, operation by command
panel, troubleshooting, transfering service data transfer, etc.
Separated Video or Super-Video is a standard for video cabling that splits
the information into two separate signals: one carries brightness (luminance)
and the other carries color (chrominance). In contrast to composite video,
S-Video has a sharper picture. Nowadays, DVD players, some VCRs, and many
high-end televisions all support S-Video.
The process of converting an analog signal (such as a picture or a soundtrack)
into digital form. In the case of a picture, a large number of small,
evenly spaced areas are taken and each represented as one or more numbers
for brightness (luminance) and color. These areas are referred to as picture
elements or pixels. The more samples are taken, the more accurate (with
higher resolution) an image can be reconstructed from the samples. For
DVD, the image is 720 samples wide by 480 samples high for a total of
345,600 samples (may vary slightly). Even analog TV has sampling -- each
scan line is a discrete (as in digital) sample in the vertical direction
although it is continuous (analog) in the horizontal direction.
The reformatting of video or digital pictures to occupy a different number
of scan lines or a different horizontal or vertical pixel count. Also
referred to as "resampling". This is done to zoom an image on the screen
without spreading out the existing scan lines, or to change the video
from one format to another, for example HDTV to NTSC or NTSC to SECAM.
SDTV (Standard Definition Television)
Standard Definition TV is one of the new standards for broadcasting and
receiving digital television (DTV). SDTV includes 480 lines in both interlaced
and progressively scanned formats, (although the latter has recently been
renamed EDTV or Enhanced Digital TV), and offers significant improvement
over today's NTSC picture. The new DTV channel can be compressed to provide
four, five or more SDTV programs within the same bandwidth required for
one channel of NTSC television (the current U.S. standard).
Sequential Couleur avec Memoire is the television broadcast standard in
France, the Middle East, and most of Eastern Europe. SECAM uses a similar
timing and resolution to PAL, and is one of three main television standards
throughout the world.
Serial Digital Interface (SDI)
Serial Digital Interface (SDI) is an SMPTE standard for digital video
transmission over coaxial cable. The SDI signal can also contain up to
four independent digital audio signals along with the video signal. Two
variations of SDI standard exist, based on the data rate: standard-definition
(SD)-SDI and high-definition (HD)-SDI. The SDI standard is widely used
in broadcasting and the video production industry because of the ability
to transmit video signals over long distances with no loss of information.
A data I/O port on the computer enabling other devices or computers to
link with the computer. Also referred to as RS-232C or COM port.
Society of Motion Picture and Television Engineers
Super VGA is an extension to the original VGA standard, and allows resolutions
Super XGA resolution is 1280x1024 pixels
Super XGA+ resolution is 1400x1050 pixels. It is a hybrid between SXGA
and UXGA found on some LCD screens for laptop PCs.
There are several types of display devices that can be used as a television.
Direct View Televisions are based on large CRTs (cathode ray tubes) that
project the image onto a the surface of a phosphor-lined glass screen
which you view directly, hence the name. Projector TVs fall into two categories,
those that project the image onto the front (viewed) surface of a reflective
screen and those that project onto the rear surface of a translucent screen.
Both types can be based on CRTs, LCDs (liquid crystal displays), DMDs
(digital micromirror device, also known as DLP) or some other technology.
Flat Panel Televisions are typically based on plasma or LCD technology,
and can be thought of as inherently progressive in that the entire image
is drawn at one time with no interlacing of odd and even lines. Because
of this capability, most of these devices are capable of acting as computer
monitors as well as being used as televisions. Large Computer Monitors
can be used as televisions, but a big drawback is that they are typically
not as bright as televisions. In addition, with computer monitors, you
won't have access to all of the fancy Picture-in-Picture, stereo audio
and other features typically found in today's TVs.
TV sets all come with built in tuners, which select the specified channel
out of all of the channels broadcast, and convert it into a baseband (non-modulated)
video signal for display. Plasma Display TVs may require a separate tuner,
which may be a satellite or a cable set-top box.
Condition when the picture size is adjusted so that strips of unused screen
area are along all borders. Computer users sometimes leave their monitors
adjusted this way to guarantee that material such as the "start button"
in the lower corner of the Windows screen does not disappear beyond the
edge. Also on some TV sets the edges of the picture suffer distortion
when extended all the way to the picture tube edge. See also overscan.
To convert a video format to a higher resolution or higher quality form.
For high-definition television, it is used to describe the process of
reformatting a SDTV (480i/480p) signal to an HDTV format (1080i). This
may not actually increase picture resolution, but allows the program to
be accepted through the set's HDTV inputs.
Ultra XGA - describes 1600x1200 pixel resolution.
Number of horizontal lines that can be output by a video display. Higher
resolutions result in better quality pictures. Television resolution is
often stated in vertical resolution, for example the NTSC (analog) television
standard used in the United States has a vertical resolution of 525 -
there are 525 horizontal lines to make up the image. It should be noted
that DVD and some digital broadcasts (satellite, digital cable) are the
only sources that actually provide the maximum vertical resolution (or
at least close to it). Vertical resolution for high definition television
is set at either 1080 lines (1080i = 1080 interlaced lines) or 720 lines
(720p = 720 non-interlaced lines).
Video Electronics Standards Association - An association whose mission
is to promote and develop timely, relevant, open display and display interface
standards, ensuring interoperability, and encouraging innovation and market
Video Graphics Array is a video standard that allows for resolutions up
to 640x480 with up to 16 colors, or 320x200 resolution with 256 colors.
Today, however, VGA refers to a 640x480 format. Higher resolutions have
now mostly replaced VGA, but VGA compatibility remains an important part
of most graphics cards.
Electronic device used to perform scaling, usually with a choice of scalings
not necessarily an even multiple or fraction of the original scan line
or pixel count.
Refers to a video program whose picture has a wider aspect ratio than
An analog computer video format with 768 visible scan lines each normally
representing 1024 pixels across.
Y, PB, PR
Also called "component video". Generally used where a digital TV signal
source is used. The video signal is separated into its component parts
of brightness and color differentials. The most advanced method for interconnecting
decoded video data. Also sometimes referred to as Y, Cr, Cb, where a video
signal is separated into components of brightness and color.
Luminance and Chrominance (color) video signals, respectively.
Learn About Deinterlacing
Deinterlacing: the conversion of a video signal from
interlaced to progressive
Modern pixel-based displays (LCD, DLP, LCOS, plasma,…) are progressive
scan and require progressively scanned video sources, whereas
many older video devices use the older interlaced scan technology.
Interlaced Scan: a complete image frame is encoded in
two fields - one containing all the odd lines, and the next containing
all the even lines. When displayed, the image is drawn with all the odd
lines being scanned from top to bottom, followed by all the even lines
top to bottom. Sixty separate fields are shown every second.
Examples of interlaced signals:
Standard Definition (480i): DVD, SD broadcast / cable, VCR, laserdisc,…
High Definition (1080i): HD broadcast / cable, DVHS, game consoles,…
Progressive Scan: a complete image frame contains all
the lines of the picture, in order, from top to bottom. When displayed,
each image frame is drawn in a single scan from top to bottom. Sixty complete
frames are shown per second.
Examples of progressive signals:
Standard Definition (480p): progressive scan DVD players, progressive
output from set top boxes
High Definition (720p): HD broadcast / cable, game consoles VESA (XGA@60HZ):
Home Theater PC (HTPC), Laptop
The problems of Deinterlacing
There are a number of challenges in converting an interlaced video source
into progressive scan format. Here are two of the main issues that a video
deinterlacer has to deal with:
Motion Adaptive - allow for the movement of objects in
the time between the two interlaced fields of a frame. Edges should be
smoothed, but without losing detail. Our eyes are very good at detecting
the slightest jagged edge, or hesitation in movement.
Film Source - detect original film source material that
has been adapted for dvd and reverse that process (apply inverse 3:2 pulldown).
Works on film are generally adapted to TV format by repeating every 3rd
or 5th frame in order to bring it up to the right number of frames per
second. When deinterlacing, it is important to allow for the duplicate
frames to keep movement and edges smooth.
Not all Deinterlacers are created equal
Displays may have their own built-in deinterlacers, but these tend to
be of inferior quality. Artifacts resulting from the slight time difference
between interlaced fields can cause strange effects, and flickering may
be a problem.
DVDO's Precision Deinterlacing™ technology delivers
the image quality demanded by today's large-screen, high-resolution displays.
It eliminates many of the artifacts found in common deinterlacers to produce
a smooth image, free of artifacts such as jagged edges and combing.
Precision Deinterlacing features five-field motion-adaptive deinterlacing
and edge-adaptive processing for video sources, along with advanced cadence
detection for film and animation sources. All processing is performed
at full 10-bit resolution to preserve all the detail and subtle nuances
in the video source. Edge-adaptive processing uses an adaptive, continuous-angle
detection algorithm to accurately identify and smooth image edges.
Unique, "any-cadence" processing automatically locks to the wide variety
of film and animation cadences found in current video sources, including
non-standard cadences, and will track right through many types of "bad
edits" and cadence changes. The Precision Deinterlacing Card also features
operating modes for special video applications, such as low-latency processing
for video games, where timing is essential.