High Def Forum - Your High Definition Community & High Definition Resource  


Hello all! The following is a High Def Glossary. If you would like to add to this list please do so by e-mailing your suggestions. Your help is greatly appreciated!

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 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 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.


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 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 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 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 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.


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.


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 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).


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, 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 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 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 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.


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.


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.


See "codec." A device or program that translates encoded data into its original format (i.e., it decodes the data.)


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 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.


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.


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 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).


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.


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 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.


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.


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 Institute of Electrical and Electronics Engineers; a nascent standard for connecting digital television and computers to various components and peripherals, such as Digital VHS, set-top HDTV tuner boxes and digital video camcorders.

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 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.


The unit of measure for light output of a projector.


The brightness or black-and-white component of a color video signal. Determines the level of picture detail.


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.


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 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.


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.


This acronym is short for the "Super Video Graphics Array" display mode. SVGA resolution is 800 x 600 pixels.


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.


Ultra high frequency, the range used by TV channels 14 through 69.


Process by which a standard definition picture is changed to a simulated high-definition picture.


This acronym is short for the "Video Graphics Array" display mode. VGA resolution is 640 x 480 pixels.


Very high frequency, the range used by TV channels 2 through 13.


Widescreen TV is the television with 16:9 aspect ratio. 16:9 is the 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 units of width for every 9 units of height.