I (In Phase) Signal: One of two color difference signals in the NTSC system. The other signal is the Q (Quadrature) signal.
I-picture: Intra-coded Picture A picture coded using information only from itself.
Icon: A graphic associated with a computer function to be performed; a term referring to symbols used for computer commands on computers equipped with a Graphic User Interface. (See GUI).
IEEE: Institute of Electrical & Electronics Engineers
IF: Intermediate frequency: Lower frequency that is more easily handled by low cost consumer circuitry
Image Intensifier: A device used in law enforcement, surveillance, and security applications that can amplify the image output signal of an imager, producing a usable picture in extremely low-light situations.
Image Processing: Techniques that manipulate the pixel values of an image to alter or improve image quality. Examples include brightness or contrast correction, color correction, changing size (scaling), or changing the shape of the image (warping).
Impedance: An expression of the electrical resistance in a circuit that is the total opposition to electric current flow. Impedance is measured in Ohms (W). A standard video signal has an impedance of 75W.
Insert Edit: The insertion of a segment into an already recorded series of segments on a videotape. Allows separate editing of video and audio tracks.
In the clear: Video signal delivered without any scrambling or encoding
Intelligent Device: Any device that contains its own processor. Synonym: "Smart" device.
Interactive: Involving the active participation of the user in directing the flow of the computer or video program. A system which exchanges information with the viewer, processing the viewer's input in order to generate the appropriate response within the context of the program--as opposed to a linear program in which the viewer passively watches from beginning to end.
Interactive Graphics: 1. An audiographic teleconferencing system which allows all sites to modify and change a commonly shared electronic diagram or graphic. 2. Computer graphics.
Interactive Media: 1. Media which involves the viewer as a source of input to determine the content and duration of a message, permitting individualized program material. 2. A philosophy of media production designed to take maximum advantage of random access, computer-controlled videotape and videodisc players.
Interactive Video: The combination of microprocessors and video where the sequence of information is determined by the user's response.
Interconnect: The transmission of one or more services on two or more cable systems to create a larger subscriber base, generally for advertising sales purposes. Interface: An electronic device which allows dissimilar components in a system to communicate. The connection between two devices, such as a computer and a peripheral, for example.
Interface: 1.) A set of software instructions that allows the editing system to control a peripheral device such as a VTR, ATR, DVE or switcher. The better the interface, the greater the ease with which the operator can assemble a program.
2.) A signal format for the transmission of information (analog or digital) from one device to another device. It converts signals from one device into a format that can be processed by the second device.
Interlace: The pattern of two separate field scans when they join to form a complete video frame. As the video picture is transmitted, the first field picks up even-numbered scan lines, the second picks up odd-numbered ones. The two lace together to form a single, complete frame. (See Field and Frame).
Interlace Scanning: 1.)A method of scanning in which one-half the total lines (262.5) are scanned in one field (even-numbered lines), and the other half of the total number of lines are scanned in the next field (odd-numbered lines). Thus, adjacent lines of a complete picture (one-frame) belong to successive fields.
2.) A bandwidth reducing technique in which each adjacent line of a complete picture (one frame) are transmitted, processed and displayed in alternate fields.
Interline Transfer (IT) Device: A CCD which employs light-shielded structures called vertical registers which are mounted next to individual pixel sensors to facilitate charge transfer. IT devices are simpler to manufacture and are, therefore, less costly than FT or FIT devices. IT sensors are used on lower-cost broadcast cameras and most industrial and consumer cameras.
Intra Coding Coding of a macroblock or picture that uses information only from that macroblock or picture.
IOD: Information on demand
IRD: Integrated receiver and decoder.
IRE Unit: Acronym for Institute of Radio Engineers. IRE units are a linear scale for measuring the relative amplitudes of the components of a television signal with a zero reference at the blanking level. In the NTSC system, the tip of horizontal sync is located at -40 IRE, while reference white is at 100 IRE, and the 1 volt peak to peak video signal is equal to 140 IRE units.
Iris: An aperture in camera lenses which controls the amount of light passing through the lens to reach the imager. The iris is required to compensate for changing lighting conditions.
ISDN: Integrated Services Digital Network A CCITF standard for integrated transmission of voice and data. Bandwidths include basic rate (144 Kbps) and primary rate 1.544 (North American) and 2.048 (Europe).
ISR: Interactive Status Reporting. A software system based on SMPTE protocol that monitors the performance of equipment.
ISO 646: An international character set standard, of which ASCII is a subset.
ISO-9000 (9001,9002,etc.): International Standards Organization. Standards for quality products and performance.
ITV: Interactive TV: A service to allow viewers to interact with televised programming. For example, a viewer could play along with a game show, choose which camera to view during a sports event, or request additional information from an advertiser.
IVDS: Interactive Video Delivery System: Interactive video services delivery that is radio based. The FCC has started lotteries for 2 providers per broadcast in major market areas. Winners are allotted 0.5 MHz of spectrum (between 218.0 and 219.0 MHz)