Glossary I-L

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I

IEEE 1394

Networking standard for PCs. Combined with 5C copy protection, is used as a two-way connection to transfer the MPEG-compressed digital bitstreams between consumer electronics items, including HDTV tuners and displays, D-VHS recorders, DVD players, and DBS receivers. Also called FireWire, iLink, …

iLink

See IEEE 1394

I.R. (Infra Red)

A range of frequencies lower than visible red light used for covert surveillance or as a low cost wireless video link.

IRIS

A mechanical diaphragm which can be controlled manually or automatically to adjust the lens aperture.

Infrared Illumination

When a scene is subject to dark conditions, active infrared illumination must be applied for best results. Active infrared illumination is a new surveillance technology that is so effective that the images produced are often mistaken for regular daytime monochrome images. Active infrared illumination is a cost-effective technology for enabling truly effective 24/7 surveillance in any lighting conditions including total darkness.

Intensifier

An electronic device that creates an output image brighter than the input (original) image. Optical amplifier.

Integrated Amplifier

A combination preamp and amplifier.

Interlace

A scanning process where every other horizontal line is scanned in one field while the alternate lines are scanned in the next field to produce a complete picture frame.

IP Address

The Internet Protocol address; a unique numeric address such as 123.231.32.2 Also see Static IP and Dynamic IP.

Iris

The adjustable opening (mechanical diaphragm) through which light can pass and be regulated.

Isobarik

Also known as compound loading. By using two low frequency drivers (generally mounted face-to-face and wired electrically out-of-phase or mounted front-to-back in a shallow tube and wired electrically in phase) you can halve the volume of the cabinet without reducing the low frequency extension of the subwoofer.

J

JPEG

A digital image format commonly used in digital recording, for storing high-quality color and grayscale photographs in compressed bitmap form.

K

Kelvin

One of the basic physical units of measurement for temperature. The scale is the same as the Celsius, but the 0ºK starts from -273ºC. Also the unit of measurement of the temperature of light is expressed in Kelvin’s or K. In color recording, light temperature affects the color values of the lights and the scene that they illuminate.

KHz

Kilohertz. Thousand Hertz.

Kilobyte

1024 bytes

L

LAN

Local Area Network. A short distance data communications network (typically within a building or campus) used to link computers and peripheral devices.

Letterbox

Format used widely on laser disc and many DVDs to fit wide-aspect-ratio movies (1.85:1 and 2.35:1, for example) into a smaller frame, such as the 1.78:1 area of an anamorphic DVD or the 1.33:1 area of a laser disc or video tape. The image is shrunk to fit the screen, leaving blank space on the top and bottom. This process sacrifices some vertical detail that must be used to record the black bars.

Line-Level (Low-Level)

A level of electrical signals too low to make the average speaker move sufficiently. Amplifiers receive line-level signals and amplify them to speaker level.

Line-of-sight

Range refers to the ideal broadcast range of wireless audio/video link (transmitter and receiver) systems. Line-of-sight means the range when there is a visible pathway between the transmitter antenna and the receiver antenna.

Liquid crystal display (LCD)

A screen for displaying video/text/graphics based on a technology called liquid crystal, where minute currents change the reflectiveness or transparency of the screen. The advantages of LCD screens are very small power consumption (can be easily battery driven) and low price of mass-produced units.

Low Light (or low lux)

Sensitivity refers to a camera's performance under low lighting conditions. Specifications list the absolute lowest light level at which some pixels will be altered.

Luminance (Y)

The part of a video signal that consists of the monochrome data.

Lux

A unit measuring the intensity of light. It is defined as the illumination of a surface when luminous flux of 1 lumen falls on an area of 1 m2. It is also known as lumen per square meter, or meter-candelas.One foot-candle = 10 lux.

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