See Video installation.


For the purpose of variable media guidelines, to say that an artwork must be "installed" implies that its physical installation is more complex than simply hanging it on a nail. Examples of artworks with this behavior are works that scale to fill a given space or make use of unusual placement such as the exterior of a building or a public plaza. For such works, the variable media questionnaire tracks issues of site-specific placement as well as scale, public access, and lighting.[Variable Media]


While the word is most commonly applied to electronic media such as computer-driven installations and Web sites, interactivity also describes installations that allow visitors to manipulate or take home components of a physical artwork. The variable media questionnaire tracks such considerations as the type of interface; the method by which visitors modify the work; and the form in which traces of such input are recorded. [Variable Media]


The ability to exchange recordings made on machines made by one manufacturer with those recorded on machines made by another manufacturer without affecting the playback of video. [AMIA]


(Short for interlaced scanning) A system of video scanning whereby the odd- and even- numbered lines of a picture are transmitted consecutively as two separate interleaved fields. Also called line interlace. See noninterlaced.[BAVC]


Technique used to reduce flicker caused when the first created video field fades while the next is being written. [Projector People]

Internet art

Art made specifically for viewing or distributing on the Internet.[Variable Media]

Invert image

Many projectors that are ceiling mounted are mounted upside down. Invert image corrects the image digitally so your projected image is not also upside down. [Projector People]

IRE (Institute of Radio Engineers)

Units of measurement dividing the area from the bottom of sync to peak white level into 140 equal units. 140 IRE equals 1V p-p. The range of active video is 100 IRE. [BAVC]

ISO (International Standards Organization)

The organization, founded in 1947 and made up of representatives from national standards bodies, that produces worldwide industrial and commercial standards. [EAI]


A powerful, Web-friendly programming language developed by Sun Microsystems that gives programmers substantial control over the look and function of the interface. [Variable Media]


Small and rapid variations in a waveform due to mechanical disturbances, changes in the characteristics of components, supply voltages, imperfect synchronizing signals, circuits, etc. [BAVC]


Process of moving a videotape forward or backward one frame at a time.[ScreenSound Australia]


AKA Joint Photographic Experts Group. An international group, which is working, on a proposed universal standard for the digital compression and decompression of still images used in computer systems. The JPEG idea reduces image size as much as 65:1 and still maintains image integrity by getting rid of subtle color differences the human eye can not see. [Projector People]


A (or kilobyte) unit of information or of computer storage equal to one thousand bytes. [EAI]

Keystone correction

A projectors ability to correct the effects of "pointing up" or "pointing down" at a screen enabling the projector user's audience to view a rectangular image rather than one with a wider top or bottom. [Projector People]


The distortion (usually a wide-top narrow-bottom effect) of a projected image caused by a projector "pointing up" or "pointing down" at its screen. Named after its similarity in shape to the keystone used in constructing an arch. [Projector People]

Laser disc

A form of optical media that, unlike DVD, stores video as a composite analog signal. The laser disc was first introduced by Philips and MCA in 1972, and has been on the market since 1978. Laser discs can be glass or plastic. There are essentially two types of laser disc: those mastered for constant linear velocity (CLV) and those mastered for constant angular velocity (CAV). CAV store approximately 30 minutes of video, can be controlled in a frame-accurate way and can be still framed. CLV discs can store approximately one hour of video but cannot be controlled frame-accurately and cannot be still-framed. Once a popular display format for many artists, the laser disc has now largely been superseded by DVD. Laser discs could not handle saturated areas of color, and would produce artifacts appearing as herring bone patterns. CAV discs did, however, have the advantage of frame-accurate external control. [BAVC]

LCD monitor (Liquid Crystal Display)

A monitor that uses a liquid crystal display. LCD monitors are typically flat screens that need less power than other displays [EAI]

LCD projector (Liquid Crystal Display)

A projector that uses a liquid crystal display. LCD projectors place a small LCD panel, almost always color, in front of a bright lamp, with the input imagery projected through a lens on a flat surface. [EAI]


The first part of a magnetic tape before the start of the recording. For a VHS tape, this is a clear, non-magnetic material used to determine where to stop the tape during rewind. For other tapes, the leader may be a non-magnetic material spliced on the beginning of the tape (like VHS) or it may be the beginning section of the tape before the program material. This section may be unrecorded, it may contain metadata, or it may have color bars and/or audio tones. [AMIA]


A screen surface that has an embossed geometric shaped pattern that affects view/angle performance and reflection of ambient light. [Projector People]

Linear editing

A form of analog editing in which sequential edits are laid out in a linear fashion from the start to the end of the tape. Precludes inserting footage without re-recording all following edits. In contrast to nonlinear editing. [BAVC]

List server

A program that automatically routes messages via e-mail to all the participants in a discussion group. Examples of List server applications include majordomo and ListServ. [Variable Media]

Long throw lens

A lens designed for projection from the back of a room. Long throw lenses would be used a projection booth in the back of a theater, or from the back of a large classroom. A long throw lens would have to be 50 to 100 FT back to project a 10FT diagonal image. [Projector People]

Longitudinal recording

A recording format in which a slow or fast moving tape is passed by a stationary magnetic record or play (write or read) head. The recorded tracks are parallel to the edge of the tape and run the full length of the tape. [AMIA]


Video image edited in such a way that it has no (clearly defined) beginning or end. [Montevideo]

Lossless compression

Coding essentially expands to provide identical data, bit for bit, with the original source data, although the processing does introduce the possibility of errors. The compression factor of such a system is usually around 2:1. Digital Betacam is a format that employs "lossless" intra-coded compression.[BAVC]

Lossy compression

Coding does not expand to produce identical data to the source material and differences are detectable. MPEG 2 is an example of a lossy inter-coded compression standard. MPEG-2 is the compression system used for DVD. [BAVC]

LTC (Longitudinal Time Code)

Another expression for the SMPTE time code signal recorded onto the third audio track of a videocasstte tape. [BAVC]


1. Unit of light output. 2. The measure of luminous flux (the rate at which light pulses are emitted or received). For instance, one candela of light covering a square foot of surface. [ScreenSound Australia]