Windows XP Glossary

From codec to .jpg, netiquette to emoticons, pixels to PCI cards—this glossary will help you understand concepts, products, techniques, and tools that you'll be using as you do amazing things with Windows XP. The terms in this glossary were excerpted from Microsoft Computer Dictionary, 5th Edition.

A  |  B  |  C  |  D  |  E  |  F  |  G  |  H  |  I  |  K  |  L  |  M  |  N  |  O  |  P  |  Q  |  R  |  S  |  T  |  U  |  V  |  W

A

1024x768  n. A standard super VGA computer display having a resolution of 1024 columns of pixels by 768 rows of pixels. See also SVGA.

16–bit color  adj. Of, pertaining to, or characteristic of a display that can produce 216 (65,536) distinct colors. Compare 24–bit color, 32–bit color.

24–bit color  n. RGB color in which the level of each of the three primary colors in a pixel is represented by 8 bits of information. A 24–bit color image can contain over 16 million different colors. Not all computer monitors support 24–bit color, especially older models. Those that do not may use 8–bit color (256 colors) or 16–bit color (65,536 colors). Also called: true color. See also bit depth, pixel, RGB. Compare 16–bit color, 32–bit color.

32–bit color  n. RGB color that is similar to 24–bit color, with 8 additional bits used to allow for faster transfer of an image's color. See also bit depth, RGB. Compare 16–bit color, 24–bit color.

8–bit color  n. A display setting that holds up to 256 specific color entries. Any color palette attached to a picture is by definition an 8–bit palette.

Advanced Streaming Format  n. An open file format specification for streaming multimedia files containing text, graphics, sound, video, and animation. Advanced Streaming Format (ASF) does not define the format for any media streams within the file. Rather, it defines a standardized, extensible file "container" that is not dependent on a particular operating system or communication protocol, or on a particular method (such as HTML or MPEG–4) used to compose the data stream in the file. An ASF file consists of three objects: a Header object containing information about the file itself, a Data object containing the media streams, and an optional Index object that can help support random access to data within the file. The ASF specification has been submitted to the ISO (International Organization for Standardization) for consideration. Acronym: ASF. See also streaming.

alias  n. A name used to direct e–mail messages to a person or group of people on a network.

aspect ratio  n. In computer displays and graphics, the ratio of the width of an image or image area to its height. An aspect ratio of 2:1, for example, indicates that the image is twice as wide as it is high. The aspect ratio is an important factor in maintaining correct proportions when an image is printed, rescaled, or incorporated into another document.

@  n. The separator between account names and domain names in Internet e–mail addresses. When spoken, @ pronounced as "at." Therefore, user@host.com would be read as "user at host dot com."

at sign  n. See @.

audio  adj. Relating to frequencies within the range of perception by the human ear—from about 15 to 20,000 hertz (cycles per second).

audiocast  n. The transmission of an audio signal using IP protocols.

audio compression  n. A method of reducing the overall loudness of an audio signal. This is accomplished by limiting the amount of apparent distortion when the signal is played back through a speaker or transmitted through a communications link.

audio output port  n. A circuit consisting of a digital–to–analog converter that transforms signals from the computer to audible tones. It is used in conjunction with an amplifier and a speaker.

audiovisual  adj. Relating to or being any material that uses a combination of sight and sound to present information.

author  vb. To assemble multimedia components, such as graphics, text, audio, and animation, in a publication or product, for delivery on a CD–ROM or DVD or on line, to be viewed on a computer.

.avi  n. The file extension that identifies an audiovisual interleaved data file in the Microsoft RIFF format.

AVI  n. Acronym for Audio Video Interleaved. A Windows multimedia file format for sound and moving pictures that uses the Microsoft RIFF (Resource Interchange File Format) specification.


B

B1FFSlang n. A new online user who is prone to making mistakes in e–mail, newsgroup articles, instant messages, or chats that show his or her inexperience. Examples of typical mistakes made by B1FFs include sentences ending with multiple exclamation points (!!!!) and messages typed in ALL CAPS. Although it's spelled B–1(one)–F–F, the term is pronounced "bif."

bandwidth  n.  1. The difference between the highest and lowest frequencies that an analog communications system can pass as measured in Hertz (Hz) or cycles per second. For example, a telephone accommodates a bandwidth of 3000 Hz: the difference between the lowest (300 Hz) and highest (3300 Hz) frequencies it can carry. 2. The data transfer capacity, or speed of transmission, of a digital communications system as measured in bits per second (bps).

bit depth  n. The number of bits per pixel allocated for storing indexed color information in a graphics file.

bit image  n. A sequential collection of bits that represents in memory an image to be displayed on the screen, particularly in systems having a graphical user interface. Each bit in a bit image corresponds to one pixel (dot) on the screen. The screen itself, for example, represents a single bit image; similarly, the dot patterns for all the characters in a font represent a bit image of the font. In a black–and–white display each pixel is either white or black, so it can be represented by a single bit. The "pattern" of 0s and 1s in the bit image then determines the pattern of white and black dots forming an image on the screen. In a color display the corresponding description of on–screen bits is called a pixel image because more than one bit is needed to represent each pixel. See also bitmap, pixel image.

bitmap  n. A data structure in memory that represents information in the form of a collection of individual bits. A bit map is used to represent a bit image. Another use of a bit map in some systems is the representation of the blocks of storage on a disk, indicating whether each block is free (0) or in use (1). See also bit image, pixel image.

body  n.  1. In e–mail, instant messaging, and Internet newsgroups, the content of a message. The body of a message follows the header, which contains information about the sender, origin, and destination of the message.

browser CLUT  n. A color look–up table consisting of the 216 colors deemed safe when viewed with most Web browsers on most computer operating systems. See also CLUT, Websafe palette.


C

CD  n.  1. An individual compact disc, such as a CD–ROM. See also CD–ROM, compact disc (definition 2).

CD–I  n. Acronym for compact disc–interactive. A hardware and software standard for a form of optical disc technology that can combine audio, video, and text on high–capacity compact discs. CD–I includes such features as image display and resolution, animation, special effects, and audio. The standard covers methods of encoding, compressing, decompressing, and displaying stored information. See also CD–ROM.

CD player  n. Short for compact disc player. A device that reads the information stored on a CD. A CD player contains the optical equipment necessary for reading a disc's contents and the electronic circuitry for interpreting the data as it is read.

CD Plus  n. A compact disc encoding format that allows mixing of audio recordings and computer data on the same CD, without the possibility of audio equipment becoming damaged by attempting to play the data sections.

CD–R  n. Acronym for compact disc–recordable. A type of CD–ROM that can be written on a CD recorder and read on a CD–ROM drive. See also CD recorder, CD–ROM.

CD–R/E  adj. Acronym for compact disc–recordable and erasable. Of or pertaining to hardware and software for interfacing computers with both CD–R (compact disc–recordable) and CD–E (compact disc–erasable) devices. See also CD–R.

CD recorder  n. A device used to write CD–ROMs. Because a disc can be written only once on these machines, they are used most commonly to create CD–ROMs for data archives or to produce CD–ROM masters that can be duplicated for mass distribution. Also called: CD–R machine, CD–ROM burner. See also CD–ROM.

CD–ROM  n.  1. Acronym for compact disc read–only memory. A form of storage characterized by high capacity (roughly 650 megabytes) and the use of laser optics rather than magnetic means for reading data. Although CD–ROM drives are strictly read–only, they are similar to CD–R drives (write once, read many), optical WORM devices, and optical read–write drives. See also CD–I, CD–R. 2. An individual CD (compact disc) designed for use with a computer and capable of storing up to 650 megabytes of data. See also CD, disc.

CD–ROM drive  n. An electromechancial device that reads data on CD–ROMs. Most CD–ROM drives have a SCSI interface, although some are connected to a PC via a controller for a disk drive. Data is read through a small laser that is focused on the surface of the CD–ROM through optical mirrors in the read/write head. A spindle and drive motor revolve the CD–ROM, so all data, which is stored in spirals from the center, can be read. CD–ROM drives vary in the access time to locate a track on the CD–ROM and the seek time to move the read/write head. Also called: CD drive. See also CD–ROM, compact disc.

CD–ROM jukebox  n. A CD–ROM player that can contain up to 200 CD–ROMs and is connected to a CD–ROM drive in a personal computer or workstation. A user can request data from any of the CD–ROMs in the jukebox, and the device will locate and play the disk that contains the data. Although only one CD–ROM can be played at a time, if multiple CD–ROM jukeboxes are each connected to separate CD–ROM drives that are daisy–chained together to the computer, more than one CD–ROM can be used at a time. See also CD–ROM, CD–ROM drive.

CD–ROM/XA  n. Short for CD–ROMExtended Architecture. An extended CD–ROM format developed by Philips, Sony, and Microsoft. CD–ROM/ XA is consistent with the ISO 9660 (High Sierra) standard, with further specification of ADPCM (adaptive differential pulse code modulation) audio, images, and interleaved data. See also CD–ROM, High Sierra specification.

CD–RW  n. Acronym for compact disc–rewritable. The technology, equipment, software, and media used in the production of multiple–write CDs (compact discs).

CDV  n.  1. Acronym for compressed digital video. The compression of video images for high–speed transmission. 2. Acronym for compact disc video. A 5–inch videodisc. See also videodisc.

CLUT  n. Acronym for Color Look Up Table. In digital graphics applications, a specific set of colors used in the creation of graphics. When a graphic is created or edited, the user may specify a CLUT that corresponds with the needs of print, Web, or other destination media. In Web design, a specific CLUT of browser–safe colors is used to be certain graphics and designs will display consistently across different platforms and with different browsers. See also browser CLUT, websafe palette.

CMY  n. Acronym for cyan–magenta–yellow. A model for describing colors that are produced by absorbing light, as by ink on paper, rather than by emitting light, as on a video monitor. The three kinds of cone cells in the eye respond to red, green, and blue light, which are absorbed (removed from white light) by cyan, magenta, and yellow pigments, respectively. Percentages of pigments in these subtractive primary colors can therefore be mixed to get the appearance of any desired color. Absence of any pigment leaves white unchanged; adding 100 percent of all three pigments turns white to black. Compare CMYK, RGB.

CMYK  n. Acronym for cyan–magenta–yellow–black. A color model that is similar to the CMY color model but produces black with a separate black component rather than by adding 100 percent of cyan, magenta, and yellow. See also CMY.

codec  n.  1. Short for coder/decoder. Hardware that can convert audio or video signals between analog and digital forms. 2. Short for compressor/decompressor. Hardware or software that can compress and uncompress audio or video data. See also compress, uncompress. 3. Hardware that combines the functions of definitions 1 and 2.

color  n. In physics, the component of the human perception of light that depends on frequency. For light of a single frequency, color ranges from violet at the high–frequency end of the visible–light band (a small portion of the total electromagnetic spectrum) to red at the low–frequency end. In computer video, color is produced by a combination of hardware and software. Software manipulates combinations of bits that represent the distinct shades of color that are destined for particular positions on the screen (characters or individual dots, called pixels). The video adapter hardware translates these bits into electrical signals, which in turn control the brightnesses of different–colored phosphors at the corresponding positions on the screen of the monitor CRT. The user's eye unites the light from the phosphors to perceive a single color. See also color model, color monitor, monitor, RGB, video, video adapter.

color depth  n. The number of color values that can be assigned to a single pixel in an image. Also known as bit depth, color depth can range from 1 bit (black and white) to 32 bits (over 16.7 million colors). See also bit depth.

colorimeter  n. A device that evaluates and identifies colors in terms of a standard set of synthesized colors.

color look–up table  n. A table stored in a computer's video adapter, containing the color signal values that correspond to the different colors that can be displayed on the computer's monitor. When color is displayed indirectly, a small number of color bits are stored for each pixel and are used to select a set of signal values from the color look–up table. Also called: color map, color table, video look–up table. See also palette (definition 2), pixel.

Color Look Up Table  n.  See CLUT.

color management  n. The process of producing or reproducing accurate, consistent color across any of a variety of color input, output, and display devices. Color management includes, but is not limited to, accurate conversion of RGB input from input devices such as a scanner or a camera or from display devices such as a monitor to CMYK output for an output device such as a printer. Color management also encompasses application of a device profile, which contains information on color behavior for the printer or other device on which the image will be reproduced, and allowance for environmental variations such as humidity and lighting. See also CMYK, RGB.

color management system  n. A technology designed to calibrate, characterize, and process color production and reproduction across a variety of color input, output, and display devices. See also color management.

color model  n. Any method or convention for representing color in desktop publishing and graphic arts. In the graphic arts and printing fields, colors are often specified with the Pantone system. In computer graphics, colors can be described using any of several different color systems: HSB (hue, saturation, and brightness), CMY (cyan, magenta, and yellow), and RGB (red, green, and blue). See also CMY, process color, RGB, spot color.

color monitor  n. A video display device designed to work with a video card or an adapter to produce text or graphics images in color. A color monitor, unlike a monochrome display, has a screen coated internally with patterns of three phosphors that glow red, green, and blue when struck by an electron beam. To create colors such as yellow, pink, and orange, the three phosphors are lighted together in varying degrees. A video card that uses large groups of bits (6 or more) to describe colors and that generates analog (continuously variable) signals is capable of generating an enormous potential range of colors on a color monitor. See also color, color model.

color scanner  n. A scanner that converts images to a digitized format and is able to interpret color. Depth of color depends on the scanner's bit depth—its ability to transform color into 8, 16, 24, or 32 bits. High–end color scanners, commonly used when output is to be printed, are able to encode information at a high resolution or number of dots per inch (dpi). Low–end color scanners encode information at a resolution of 72 dpi and are commonly used for computer screen images not intended for printing. See also resolution (definition 1), scanner.

color separation  n.  1. The process of printing the colors in a document as separate output files, each of which is to be printed using a different–colored ink. There are two types of color separation: spot color separation and process color separation. See also color model, process color, spot color. 2. One of the output files produced by a color document, to be printed in its own color of ink.

color space  n. A means of describing color in digital environments. RGB is the most common color space on the Web, and with other color, the most common color space viewed on computer displays, while CMYK is the main color space for desktop publishing and other digital print media.

compact disc  n.  1. An optical storage medium for digital data, usually audio. A compact disc is a nonmagnetic, polished metal disc with a protective plastic coating that can hold up to 74 minutes of high–fidelity recorded sound. The disk is read by an optical scanning mechanism that uses a high–intensity light source, such as a laser, and mirrors. Also called: optical disc. 2. A technology that forms the basis of media such as CD–ROM, CD–ROM/XA, CD–I, CD–R, DVI, and PhotoCD. These media are all compact disc–based but store various types of digital information and have different read/write capabilities. Documentation for compact disc formats can be found in books designated by the color of their covers. For example, documentation for audio compact discs is found in the Red Book. See also CD–I, CD–R, CD–ROM, CD–ROM/XA, DVI, PhotoCD. 3.SeeCD.

compact disc–interactive  n. See CD–I.

compact disc player  n. See CD player.

compact disc–recordable  n. See CD–R.

compact disc–recordable and erasableadj. SeeCD–R/E.

compact disc–rewritable  n. See CD–RW.

compress  vb. To reduce the size of a set of data, such as a file or a communications message, so that it can be stored in less space or transmitted with less bandwidth. Data can be compressed by removing repeated patterns of bits and replacing them with some form of summary that takes up less space; restoring the repeated patterns decompresses the data. Lossless compression methods must be used for text, code, and numeric data files; lossy compression may be used for video and sound files. See also lossless compression, lossy compression.

compressed digital video  n. See CDV (definition 1).

compressed disk  n. A hard disk or floppy disk whose apparent capacity to hold data has been increased through the use of a compression utility, such as Stacker or Double Space.

crop marks  n.  1. Lines drawn at the edges of pages to mark where the paper will be cut to form pages in the final document. 2. Lines drawn on photographs or illustrations to indicate where they will be cropped, or cut.


D

decompress  vb.  See uncompress.

desktop publishing  n. The use of a computer and specialized software to combine text and graphics to create a document that can be printed on either a laser printer or a typesetting machine. Desktop publishing is a multiple–step process involving various types of software and equipment. The original text and illustrations are generally produced with software such as word processors and drawing and painting programs and with photograph–scanning equipment and digitizers. The finished product is then transferred to a page–makeup program, which is the software most people think of as the actual desktop publishing software. This type of program enables the user to lay out text and graphics on the screen and see what the results will be; for refining parts of the document, these programs often include word processing and graphics features in addition to layout capabilities. As a final step, the finished document is printed either on a laser printer or, for the best quality, by typesetting equipment.

desktop video  n. The use of a personal computer to display video images. The video images may be recorded on video tape or on a laser disc or may be live footage from a video camera. Live video images can be transmitted in digital form over a network in video conferencing. Acronym: DTV.

digital  adj.1.A reference to something based on digits (numbers) or their representation. 2. In computing, analogous in use, though not in meaning, to binary because the computers familiar to most people process information coded as different combinations of the binary digits (bits) 0 and 1.

digital audio disc  n. An optical storage medium for recording digitally encoded audio information. See also compact disc (definition 1).

digital audio tape  n. A magnetic tape storage medium for recording digitally encoded audio information. Acronym: DAT.

digital audio/video connector  n. An interface on some high–end video cards or TV tuner cards that allows the simultaneous transmission of digital audio and video signals. Also called: DAV connector. See also video adapter.

digital camera  n. A type of camera that stores photographed images electronically instead of on traditional film. A digital camera uses a CCD (charge–coupled device) element to capture the image through the lens when the operator releases the shutter in the camera; circuitry within the camera then stores the image captured by the CCD in a storage medium such as solid–state memory or a hard disk. After the image has been captured, it is downloaded by cable to the computer using software supplied with the camera. Once stored in the computer, the image can be manipulated and processed much like the image from a scanner or related input device. See also digital photography.

digital communications  n. Exchange of communications in which all information is transmitted in binary–encoded (digital) form.

digital photography  n. Photography by means of a digital camera. Digital photography differs from conventional photography in that a digital camera does not use a silver halide–based film to capture an image. Instead, a digital camera captures and stores each image electronically. See also digital camera.

digital picture frame  n. Electronic device used in displaying digital photos and graphics while giving the outward appearance of a traditional picture frame. Digital picture frames allow users to rotate photos within the frame at specified intervals, display a series of photos as a slide show, or use an Internet connection to download photos, order prints, or send customized photo sets to others.

digital recording  n. The storage of information in binary–encoded (digital) format. Digital recording converts information—text, graphics, sound, or pictures—to strings of 1s and 0s that can be physically represented on a storage medium. Digital recording media include computer disks and tapes, optical (or compact) discs, and ROM cartridges of the type used for some software and many computer games.

Digital Rights Management  n. See DRM.

digital video  n. Video images and sound stored in a digital format. Acronym: DV.

digital video disc  n. The next generation of optical disc storage technology. With digital video disc technology, video, audio, and computer data can be encoded onto a compact disc (CD). A digital video disc can store greater amounts of data than a traditional CD. A standard single–layer, single–sided digital video disc can store 4.7 GB of data; a two–layer standard increases the single–sided disc capacity to 8.5 GB. Digital video discs can be double–sided with a maximum storage of 17 GB per disc. A digital video disc player is needed to read digital video discs; this player is equipped to read older optical storage technologies. Advocates of the digital video disc intend to replace current digital storage formats, such as laser disc, CD–ROM, and audio CD, with the single digital format of the digital video disc. Acronym: DVD. Also called: digital versatile disc. See also digital video disc–ROM.

digital video disc–erasable  n. A proposed extension to the digital video disc recording format to allow multiple re–recording by a consumer. Acronym: DVD–E. Also called: digital video disc–ROM.

digital video disc–recordable  n. A proposed extension to the digital video disc recording format to allow one–time recording by a consumer. Acronym: DVD–R.

digital video disc–ROM  n. A computer–readable version of a digital video disc containing either 4.7 or 8.5 GB of storage per side, the larger if 3M's dual–layer "2P" technology is used. Acronym: DVD–ROM. Also called: digital video disc–erasable. See also digital video disc.

digital watermark  n. A unique identifier embedded in a file to deter piracy and prove file ownership and quality. Digital watermarking is often used with graphics and audio files to identify the owner's rights to these works.

digitize  vb. To convert any continuously varying (analog) source of input, such as the lines in a drawing or a sound signal, to a series of discrete units represented in a computer by the binary digits 0 and 1. Analog–to–digital converters are commonly used to perform this translation.

direct digital color proof  n. A test sheet produced by a lower–cost output device, such as a color laser printer, to serve as an approximation of what the final image will look like when produced on professional–quality printing equipment. A direct digital color proof does not involve color separation, as in traditional proofs. Instead, a direct digital color proof is printed in all colors at one time on a single page, resulting in somewhat lower quality compared with traditional separation methods but having the advantages of increased speed and reduced cost. Acronym: DDCP. Also called: digital proof. See also color separation (definition 1).

DirectX  n. A set of Microsoft technologies that provide developers with the tools needed to create sophisticated multimedia applications on Windows–based computers. DirectX consists of components making up two integrated layers. The Foundation layer provides low–level functions, such as support for input devices, designed to ensure that applications can run on—and take full advantage of—Windows–based hardware. The Media layer, above the Foundation layer, provides high–level services, such as support for media streaming and animation, that are needed in creating applications incorporating such features as surround sound, video, and 3–D animation. DirectAnimation, DirectSound, and other similarly named application programming interfaces (APIs) are members of the DirectX family.

disc  n. A round, flat piece of nonmagnetic, shiny metal encased in a plastic coating, designed to be read from and written to by optical (laser) technology. It is now standard practice to use the spelling disc for optical discs and disk in all other computer contexts, such as floppy disk, hard disk, and RAM disk. See also compact disc.

disk  n.  1. A round, flat piece of flexible plastic coated with a magnetic material that can be electrically influenced to hold information recorded in digital (binary) form and encased in a protective plastic jacket to protect the disk from damage and contamination. Also called: floppy, floppy disk, microfloppy disk. Compare compact disc, disc.

dithering  n. A technique used in computer graphics to create the illusion of varying shades of gray on a monochrome display or printer, or additional colors on a color display or printer. Dithering relies on treating areas of an image as groups of dots that are colored in different patterns. Akin to the print images called halftones, dithering takes advantage of the eye's tendency to blur spots of different colors by averaging their effects and merging them into a single perceived shade or color. Depending on the ratio of black dots to white dots within a given area, the overall effect is of a particular shade of gray. Dithering is used to add realism to computer graphics and to soften jagged edges in curves and diagonal lines at low resolutions. See also halftone.

Downloadable Sounds  n. A standard for synthesizing wave sounds from digital samples stored in software. The DLS level 1 and level 2 standards are published by the MIDI Manufacturers Association. Acronym: DLS.

DRM  n. Acronym for Digital Rights Management. A group of technologies developed to protect intellectual property from online piracy by controlling who can view protected content and in what form. A DRM package may allow the purchaser to view protected content, but prevent printing or forwarding. Content may also be set to expire after a set amount of time or if distributed to multiple users. DRM technology is meant to protect multiple forms of digital and analog content, and includes encryption, digital watermarking, and content tracking software.

drum scanner  n. A type of scanner where the medium being scanned, such as a sheet of paper, is rotated around a stationary scan head. See also scanner. Compare flatbed scanner, handheld scanner.

DSL  n. Acronym for Digital Subscriber Line, a recently developed (late 1990s) digital communications technology that can provide high–speed transmissions over standard copper telephone wiring. DSL is often referred to as xDSL, where the x stands for one or two characters that define variations of the basic DSL technology. Currently, ADSL (Asymmetric DSL) is the form most likely to be provided, but even it is, as yet, available only to limited groups of subscribers.

DV  n. See digital video.

DVD  n. See digital video disc.

DVD decoder  n. A hardware or software component that allows a digital video disc (DVD) drive to display movies on your computer screen. See also digital video disc.

DVD–E  n. See digital video disc–erasable.

DVD–R  n. See digital video disc–recordable.

DVD–ROM  n. See digital video disc–ROM.

DVI  n. Acronym for Digital Video Interface. A hardware–based compression/decompression technique for storing full–motion video, audio, graphics, and other data on a computer or on a CD–ROM. DVI technology was developed by RCA in 1987 and acquired by Intel in 1988. Intel has since developed a software version of DVI, called Indeo. Also called: digital video–interactive.

DVR  n. Acronym for Digital Video Recording. Technology allowing broadcast television programming to be digitized and played back immediately. Television signals are routed through a hard drive, converted to a digital format and displayed in real–time or, at the viewer's option, on a delayed basis. DVR technology can be used like a VCR to record favorite programs in advance, with the user picking the programs to be recorded from an online programming guide. DVR capabilities can also be added to products that have related digital technologies and components, such as set–top boxes and digital TV converters.


E

emotag  n. In an e–mail message, instant message, or newsgroup article, a letter, word, or phrase that is encased in angle brackets and that, like an emoticon, indicates the attitude the writer takes toward what he or she has written. Often emotags have opening and closing tags, similar to HTML tags, that enclose a phrase or one or more sentences. For example: <joke>You didn't think there would really be a joke here, did you?</joke>. Some emotags consist of a single tag, such as <grin>. See also emoticon.

emoticon  n. A string of text characters that, when viewed sideways, form a face expressing a particular emotion. An emoticon is often used in an e–mail message, instant message, or newsgroup post as a comment on the text that precedes it. Common emoticons include :-) or :) (meaning "I'm smiling at the joke here"), ;-) ("I'm winking and grinning at the joke here"), :-( ("I'm sad about this"), :-7 ("I'm speaking with tongue in cheek"), :D or :-D (big smile; "I'm overjoyed"), and :-O (either a yawn of boredom or a mouth open in amazement). SeeInstant Messaging Emoticons. Compare emotag.

encoder  n.  1. In general, any hardware or software that encodes information—that is, converts the information to a particular form or format. For example, the Windows Media Encoder converts audio and video to a form that can be streamed to clients over a network. 2. In reference to MP3 digital audio in particular, technology that converts a WAV audio file into an MP3 file. An MP3 encoder compresses a sound file to a much smaller size, about one–twelfth as large as the original, without a perceptible drop in quality. Also called: MP3 encoder. See also MP3. Compare rip, ripper.


F

firewall  n. A security system intended to protect an organization's network against external threats, such as hackers, coming from another network, such as the Internet. Usually a combination of hardware and software, a firewall prevents computers in the organization's network from communicating directly with computers external to the network and vice versa. Instead, all communication is routed through a proxy server outside of the organization's network, and the proxy server decides whether it is safe to let a particular message or file pass through to the organization's network.

flame1  n. An abusive or personally insulting e–mail message, instant message, or newsgroup posting.

flame2  vb.  1. To send an abusive or personally insulting e–mail message, instant message, or newsgroup posting. 2. To criticize personally by means of e–mail messages, instant message, or newsgroup postings.

flatbed scanner  n. A scanner with a flat, transparent surface that holds the image to be scanned, generally a book or other paper document. A scan head below the surface moves across the image. Some flatbed scanners can also reproduce transparent media, such as slides. Compare drum scanner, handheld scanner, sheet–fed scanner.

frame grabber  n. See video digitizer.

frame rate  n.  1. The speed at which full, single–screen images are transmitted to and displayed by a raster–scan monitor. Frame rate is calculated as the number of times per second (hertz) the electron beam sweeps the screen. 2. In animation, the number of times per second an image is updated. When the frame rate exceeds about 14 frames per second, animation seems to blend into smooth motion.

freeze–frame video  n. Video in which the image changes only once every few seconds. Compare full–motion video.

full–motion video  n. Video reproduction at 30 frames per second (fps) for NTSC signals or 25 fps for PAL signals. Also called: continuous motion video. Compare freeze–frame video.


G

.gif  n. The file extension that identifies GIF bit map images. See also GIF.

GIF  n.  1. Acronym for Graphics Interchange F ormat. A graphics file format developed by CompuServe and used for transmitting raster images on the Internet. An image may contain up to 256 colors, including a transparent color. The size of the file depends on the number of colors actually used. The LZW compression method is used to reduce the file size still further. See also LZW compression. 2. A graphic stored as a file in the GIF format.

GIF animation  n. A file containing a series of graphics that are displayed in rapid sequence in a Web browser to appear as though they are a moving picture.

grabber  n.  1. A device for capturing graphical image data from a video camera or another full–motion video source and putting it into memory. Also called: frame grabber, video digitizer. 2. Any device for capturing data. 3. Software that takes a snapshot of the currently displayed screen image by transferring a portion of video memory to a file on disk. 4. In some graphics–based applications, a special type of mouse pointer.

gradient  n. A smooth progression of colors and shades, usually from one color to another color, or from one shade to another shade of the same color.

graphics accelerator  n. A video adapter that contains a graphics coprocessor. A graphics accelerator can update the video display much more quickly than the CPU can, and it frees the CPU for other tasks. A graphics accelerator is a necessity for modern software such as graphical user interfaces and multimedia applications. See also video adapter.

gray scale  n. A sequence of shades ranging from black through white, used in computer graphics to add detail to images or to represent a color image on a monochrome output device. Like the number of colors in a color image, the number of shades of gray depends on the number of bits stored per pixel. Grays may be represented by actual gray shades, by halftone dots, or by dithering. See also dithering, halftone.


H

H.320  n. An International Telecommunications Union (ITU) standard that enables interoperability among video–conferencing equipment from different manufacturers over circuit–switched services such as ISDN, thus making desktop video conferencing viable. H.320 establishes the common formats necessary to make audio and video inputs and outputs compatible and defines a protocol that makes it possible for a multimedia terminal to use audio/visual communications links and synchronization. See also ISDN, video conferencing.

H.323  n. An International Telecommunications Union (ITU) interoperability protocol enabling cross–communication of multimedia products and applications over packet–based networks. Under H.323, multimedia products offered by one vendor can work with those of another, regardless of hardware compatibility. For example, a PC can share audio and video streams over either an intranet or the Internet. Applications are thus network–, platform–, and application–independent.

H.324  n. An International Telecommunications Union (ITU) standard for simultaneously transmitting video, data, and voice over POTS (Plain Old Telephone Service) modem connections.

halftone  n. A printed reproduction of a photograph or other illustration, using evenly spaced spots of varying diameter to produce apparent shades of gray. The darker the shade at a particular point in the image, the larger the corresponding spot in the halftone. In traditional publishing, halftones are created by photographing an image through a screen. In desktop publishing, each halftone spot is represented by an area containing a number of dots printed by a laser printer or digital imagesetter. In both cases, the frequency of the halftone dots is measured in lines per inch. Higher printer resolution enables effective use of higher frequencies of halftone dots, enhancing image quality. See also dithering, gray scale.

handheld scanner  n. A type of scanner used as follows: the user passes the scan head, contained within a handheld unit, over the medium being scanned, such as a piece of paper. See also scan head, scanner. Compare drum scanner, flatbed scanner.

high–capacity CD–ROM  n. See digital video disc.

high resolution  n. The capability for reproducing text and graphics with relative clarity and fineness of detail. High resolution is achieved by using a large number of pixels (dots) to create an image in a given area. For screen displays, the resolution is stated in terms of the total number of pixels in the horizontal and vertical dimensions. For example, the VGA video adapter has a resolution of 640 by 480 pixels. In printing, resolution refers to the number of dots per inch (dpi) produced by the printer, such as 300 to 600 dpi for a desktop laser or ink–jet printer or 1000 to 2000 dpi for a production–quality imagesetter. Also called: hi–res.

High Sierra specification  n. An industry–wide format specification for the logical structure, file structure, and record structures on a CD–ROM. The specification is named after a meeting on CD–ROM held near Lake Tahoe in November 1985. It served as the basis for the international standard, ISO 9660.

HTTP streaming  n. The process of downloading streaming digital media using an HTTP server (a standard Internet server) rather than a server designed specifically to transmit streaming media. HTTP streaming downloads the media file onto a computer, which plays the downloaded file as it becomes available. See also real–time streaming.

hypermedia  n. The combination of text, video, graphic images, sound, hyperlinks, and other elements in the form typical of Web documents. Essentially, hypermedia is the modern extension of hypertext, the hyperlinked, text–based documents of the original Internet. Hypermedia attempts to offer a working and learning environment that parallels human thinking—that is, one in which the user can make associations between topics, rather than move sequentially from one to the next, as in an alphabetic list. For example, a hypermedia presentation on navigation might include links to astronomy, bird migration, geography, satellites, and radar.


I

IEEE  n. Acronym for Institute of Electrical and Electronics Engineers. A society of engineering and electronics professionals based in the United States but boasting membership from numerous other countries. The IEEE (pronounced "eye triple ee") focuses on electrical, electronics, computer engineering, and science–related matters.

IEEE 1394  n. A nonproprietary, high–speed, serial bus input/output standard. IEEE 1394 provides a means of connecting digital devices, including personal computers and consumer electronics hardware. It is platform–independent, scalable (expandable), and flexible in supporting peer–to–peer (roughly, device–to–device) connections. IEEE 1394 preserves data integrity by eliminating the need to convert digital signals into analog signals. Created for desktop networks by Apple Computer and later developed by the IEEE 1394 working group, it is considered a low–cost interface for devices such as digital cameras, camcorders, and multimedia devices and is seen as a means of integrating personal computers and home electronics equipment. FireWire is the proprietary implementation of the standard by Apple Computer. See also IEEE.

IEEE 1394 connector  n. A type of connector that enables you to connect and disconnect high–speed serial devices. An IEEE 1394 connector is usually on the back of your computer near the serial port or the parallel port. The IEEE 1394 bus is used primarily to connect high–end digital video and audio devices to your computer; however, some hard disks, printers, scanners, and DVD drives can also be connected to your computer using the IEEE 1394 connector.

IEEE 1394 port  n. A 4–or 6–pin port that supports the IEEE 1394 standard and can provide direct connections between digital consumer electronics and computers. See also IEEE 1394.

IM  n.  See instant messaging.

image  n.  1. A stored description of a graphic picture, either as a set of brightness and color values of pixels or as a set of instructions for reproducing the picture. 2. A duplicate, copy, or representation of all or part of a hard or floppy disk, a section of memory or hard drive, a file, a program, or data. For example, a RAM disk can hold an image of all or part of a disk in main memory; a virtual RAM program can create an image of some portion of the computer's main memory on disk.

image–based rendering  n.  See immersive imaging.

image color matching  n. The process of image output correction to match the same colors that were scanned or input.

image compression  n. The use of a data compression technique on a graphical image. Uncompressed graphics files tend to use up large amounts of storage, so image compression is useful to conserve space. See also video compression.

image editing  n. The process of changing or modifying a bitmapped image, usually with an image editor.

image editor  n. An application program that allows users to modify the appearance of a bitmapped image, such as a scanned photo, by using filters and other functions. Creation of new images is generally accomplished in a paint or drawing program.

image enhancement  n. The process of improving the quality of a graphic image, either automatically by software or manually by a user through a paint or drawing program. See also image processing.

image map  n. An image that contains more than one hyperlink on a Web page. Clicking different parts of the image links the user to other resources on another part of the Web page or a different Web page or in a file. Often an image map, which can be a photograph, drawing, or a composite of several different drawings or photographs, is used as a map to the resources found on a particular Web site. Older Web browsers support only server–side image maps, which are executed on a Web server through CGI script. However, most newer Web browsers (Netscape Navigator 2.0 and higher and Internet Explorer 3.0 and higher) support client–side image maps, which are executed in a user's Web browser. Also called: clickable maps.

image processing  n. The analysis, manipulation, storage, and display of graphical images from sources such as photographs, drawings, and video. Image processing spans a sequence of three steps. The input step (image capture and digitizing) converts the differences in coloring and shading in the picture into binary values that a computer can process. The processing step can include image enhancement and data compression. The output step consists of the display or printing of the processed image. Image processing is used in such applications as television and film, medicine, satellite weather mapping, machine vision, and computer–based pattern recognition. See also image enhancement, video digitizer.

image sensor  n. A light–sensitive integrated circuit or group of integrated circuits used in scanners, digital cameras, and video cameras.

imagesetter  n. A typesetting device that can transfer camera–ready text and artwork from computer files directly onto paper or film. Imagesetters print at high resolution (commonly above 1000 dpi) and are usually PostScript–compatible.

imaging  n. The processes involved in the capture, storage, display, and printing of graphical images.

immersive imaging  n. A method of presenting photographic images on a computer by using virtual reality techniques. A common immersive image technique puts the user in the center of the view. The user can pan 360 degrees within the image and can zoom in and out. Another technique puts an object in the center of the view and allows the user to rotate around the object to examine it from any perspective. Immersive imaging techniques can be used to provide virtual reality experiences without equipment such as a headpiece and goggles. Also called: image–based rendering. See also imaging.

inline graphics  n. Graphics files that are embedded in an HTML document or Web page and viewable by a Web browser or other program that recognizes HTML. By avoiding the need for separate file opening operations, inline graphics can speed the access and loading of an HTML document. Also called: inline image.

inline image  n. An image that is embedded within the text of a document. Inline images are common on Web pages. See also inline graphics.

instant messaging  n. A service that alerts users when friends or colleagues are on line and allows them to communicate with each other in real time through private online chat areas. With instant messaging, a user creates a list of other users with whom he or she wishes to communicate; when a user from his or her list is on line, the service alerts the user and enables immediate contact with the other user. While instant messaging has primarily been a proprietary service offered by Internet service providers such as AOL and MSN, businesses are starting to employ instant messaging to increase employee efficiency and make expertise more readily available to employees.

intellectual property  n. Content of the human intellect deemed to be unique and original and to have marketplace value—and thus to warrant protection under the law. Intellectual property includes but is not limited to ideas; inventions; literary works; chemical, business, or computer processes; and company or product names and logos. Intellectual property protections fall into four categories: copyright (for literary works, art, and music), trademarks (for company and product names and logos), patents (for inventions and processes), and trade secrets (for recipes, code, and processes). Concern over defining and protecting intellectual property in cyberspace has brought this area of the law under intense scrutiny.

internet  n. Short for internetwork. A set of computer networks that may be dissimilar and are joined together by means of gateways that handle data transfer and conversion of messages from the sending networks' protocols to those of the receiving network.

Internet  n. The worldwide collection of networks and gateways that use the TCP/IP suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high–speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational, and other computer systems, that route data and messages. One or more Internet nodes can go off line without endangering the Internet as a whole or causing communications on the Internet to stop, because no single computer or network controls it. The genesis of the Internet was a decentralized network called ARPANET created by the U.S. Department of Defense in 1969 to facilitate communications in the event of a nuclear attack. Eventually other networks, including BITNET, Usenet, UUCP, and NSFnet, were connected to ARPANET. Currently the Internet offers a range of services to users, such as FTP, e–mail, the World Wide Web, Usenet news, Gopher, IRC, telnet, and others. Also called: the Net.

Internet access  n.  1. The capability of a user to connect to the Internet. This is generally accomplished through one of two ways. The first is through a dialing up of an Internet service provider or an online information services provider via a modem connected to the user's computer. This method is the one used by the majority of home computer users. The second way is through a dedicated line, such as a T1 carrier, that is connected to a local area network, to which, in turn, the user's computer is connected. The dedicated line solution is used by larger organizations, such as corporations, which either have their own node on the Internet or connect to an Internet service provider that is a node. A third way that is emerging is for users to use set–top boxes with their TVs. Generally, however, this will give a user access only to documents on the World Wide Web. 2. The capability of an online information service to exchange data with the Internet, such as e–mail, or to offer Internet services to users, such as newsgroups, FTP, and the World Wide Web. Most online information services offer Internet access to their users.

Internet account  n. A generic term for a registered username at an Internet Service Provider (ISP). An Internet account is accessed via username and password. Services such as dial–in PPP Internet access and e–mail are provided by ISPs to Internet account owners.

Internet broadcasting  n. Broadcasting of audio, or audio plus video, signals across the Internet. Internet broadcasting includes conventional over–the–air broadcast stations that transmit their signals into the Internet as well as Internet–only stations. Listeners use audio Internet software, such as RealAudio. One method of Internet broadcasting is MBONE. See also RealAudio.

Internet Talk Radio  n. Audio programs similar to radio broadcasts but distributed over the Internet in the form of files that can be downloaded via FTP. Internet Talk Radio programs, prepared at the National Press Building in Washington, D.C., are 30 minutes to 1 hour in length; a 30–minute program requires about 15 MB of disk space. Acronym: ITR.

ISDN  n. Acronym for Integrated Services Digital Network. A high–speed digital communications network evolving from existing telephone services. The goal in developing ISDN was to replace the current telephone network, which requires digital–to–analog conversions, with facilities totally devoted to digital switching and transmission, yet advanced enough to replace traditionally analog forms of data, ranging from voice to computer transmissions, music, and video. ISDN is available in two forms, known as BRI (Basic Rate Interface) and PRI (Primary Rate Interface). BRI consists of two B (bearer) channels that carry data at 64 Kbps and one D (data) channel that carries control and signal information at 16 Kbps. In North America and Japan, PRI consists of 23 B channels and 1 D channel, all operating at 64 Kbps; elsewhere in the world, PRI consists of 30 B channels and 1 D channel. Computers and other devices connect to ISDN lines through simple, standardized interfaces.

ISO 9660  n. An international format standard for CD–ROM adopted by the International Organization for Standardization (ISO) that follows the recommendations embodied in the High Sierra specification, with some modifications. See also High Sierra specification.

ISP  n. Acronym for Internet service provider. A business that supplies Internet connectivity services to individuals, businesses, and other organizations. Some ISPs are large national or multinational corporations that offer access in many locations, while others are limited to a single city or region. Also called: access provider, service provider.


J

jack  n. A connector designed to receive a plug. A jack is commonly used in making audio and video connections.

JFIF  n. Acronym for JPEG File Interchange F ormat. A means of saving photographic images stored according to the Joint Photographic Experts Group image compression technique. JFIF represents a "common language" file format in that it is designed specifically to allow users to transfer JPEG images easily between different computers and applications. See also JPEG, TIFF JPEG.

Joint Photographic Experts Group  n.  See JPEG (definition 1).

.jpeg  n. The file extension that identifies graphic image files in the JPEG format. See also JPEG.

JPEG  n.  1. Acronym for Joint Photographic Experts Group. An ISO/ITU standard for storing images in compressed form using a discrete cosine transform. JPEG trades off compression against loss; it can achieve a compression ratio of 100:1 with significant loss and possibly 20:1 with little noticeable loss. 2. A graphic stored as a file in the JPEG format.

JPEG File Interchange Format  n. See JFIF.

.jpg  n. The file extension that identifies graphic images encoded in the JPEG File Interchange Format, as originally specified by the Joint Photographic Experts Group (JPEG). Inline graphics on World Wide Web pages are often .jpg files, such as coolgraphic.jpg. See also JPEG (definition 2).

jukebox  n. Software that is designed to play a list of sound files in a user–specified order reminiscent of jukeboxes used to play vinyl records. See also CD–ROM jukebox.


K

knockout  n.  1. In multicolor printing, the process of removing from one image the overlapping parts of a graphic or text that are to be printed in a different color so that ink colors will not mix. See also spot color. Compare overprint.


L

laser printer  n. An electrophotographic printer that is based on the technology used by photocopiers. A focused laser beam and a rotating mirror are used to draw an image of the desired page on a photosensitive drum. This image is converted on the drum into an electrostatic charge, which attracts and holds toner. A piece of electrostatically charged paper is rolled against the drum, which pulls the toner away from the drum and onto the paper. Heat is then applied to fuse the toner to the paper. Finally, the electrical charge is removed from the drum, and the excess toner is collected. By omitting the final step and repeating only the toner–application and paper–handling steps, the printer can make multiple copies. The only serious drawback of a laser printer is that it offers less paper–handling flexibility than do dot–matrix printers. Both multipart forms and wide–carriage printing, for example, are better handled by line printers or dot–matrix printers.

lobby page  n. A page of information about the broadcast that is displayed in the viewer's browser before the broadcast begins. It can contain a title, subject, host's name, information about the broadcast, and a countdown to the time of the broadcast.

lossless compression  n. The process of compressing a file such that, after being compressed and decompressed, it matches its original format bit for bit. Text, code, and numeric data files must be compressed using a lossless method; such methods can typically reduce a file to 40 percent of its original size. Compare lossy compression.

lossy compression  n. The process of compressing a file such that some data is lost after the file is compressed and decompressed. Video and sound files often contain more information than is apparent to the viewer or listener; a lossy compression method, which does not preserve that excess information, can reduce such data to as little as 5 percent of its original size. Compare lossless compression.

low resolution  adj. Abbreviated lo–res. Appearing in relatively coarse detail, used in reference to text and graphics in raster–oriented computer displays and printing. Low–resolution printing is comparable to draft–quality dot–matrix output printed at 125 dots per inch or less. See also resolution. Compare high resolution.

luminosity  n. The brightness of a color based on a scale from black to white on your monitor.

LZW compression  n. A compression algorithm named after Abraham Lempel and Jakob Ziv (creators of Lempel Ziv compression) and LZW designer Terry Welch that makes use of repeating strings of data in its compression of character streams into code streams. It is also the basis of GIF compression. See also GIF.


M

media  n. The physical material, such as paper, disk, and tape, used for storing computer–based information. Media is plural; medium is singular.

media stream  n. A continuous sequence of audio or audio–and–video through a network.

megapel display  n. See megapixel display.

megapixel  adj. A reference to image resolution of one million pixels or more. The term is used in reference to devices such as digital cameras, scanners, and computer monitors and display adapters.

megapixel display  n. A video display capable of displaying at least 1 million pixels. For example, a video display with a screen size of 1024 horizontal pixels and 1024 vertical pixels is a megapixel display. Also called: megapel display.

messaging  n. The use of computers and data communication equipment to convey messages from one person to another, as by e–mail, instant messaging, voice mail, or fax.

messaging application  n. An application that enables users to send messages (such as e–mail, instant message, or fax) to each other.

messaging client  n. An application program that enables its user to send or receive messages (such as e–mail, instant message, or fax) to and from other users with the help of a remote server.

microphone  n.  1. A device that converts sound waves into analog electrical signals. Additional hardware can convert the microphone's output into digital data that a computer can process; for example, to record multimedia documents or analyze the sound signal.

MIDI  n. Acronym for Musical Instrument Digital Interface. A serial interface standard that allows for the connection of music synthesizers, musical instruments, and computers. The MIDI standard is based partly on hardware and partly on a description of the way in which music and sound are encoded and communicated between MIDI devices. The information transmitted between MIDI devices is in a form called a MIDI message, which encodes aspects of sound such as pitch and volume as 8–bit bytes of digital information. MIDI devices can be used for creating, recording, and playing back music. Using MIDI, computers, synthesizers, and sequencers can communicate with each other, either keeping time or actually controlling the music created by other connected equipment.

modulation  n.  1. The process of changing or regulating the characteristics of a carrier wave vibrating at a certain amplitude (height) and frequency (timing) so that the variations represent meaningful information. 2. In computer communications, the means by which a modem converts digital information sent by a computer to the audio form that it sends over a telephone line.

monitor  n. The device on which images generated by the computer's video adapter are displayed. The term monitor usually refers to a video display and its housing. The monitor is attached to the video adapter by a cable.

morphing  n. Short for metamorphosing. A process by which one image is gradually transformed into another, creating the illusion of a metamorphosis occurring in a short time. A common motion picture special–effects technique, morphing is available in many advanced computer animation packages.

Motion JPEG  n. A standard for storing motion video, proposed by the Joint Photographic Experts Group (JPEG), that uses JPEG image compression for each frame. See also JPEG (definition 1). Compare MPEG (definition 1).

MP3  n. Acronym for MPEG Audio Layer–3. A digital audio coding scheme used in distributing recorded music over the Internet. MP3 shrinks the size of an audio file by a factor of 10 to 12 without seriously degrading the quality (CD–recording level) of the sound. MP3 files are given the file extension .mp3. Although MP3 is part of the MPEG family, it is audio–only and is not the same as the now–defunct MPEG–3 standard. See also MPEG–3.

MP3 encoder  n. See encoder.

.mpeg  n. The file extension that identifies video and sound files compressed in the MPEG format specified by the Moving Pictures Experts Group. See also MPEG.

MPEG  n.  1. Acronym for Moving Picture Experts Group. A set of standards for audio and video compression established by the Joint ISO/IEC Technical Committee on Information Technology. The MPEG standard has different types that have been designed to work in different situations. Compare Motion JPEG. 2. A video/audio file in the MPEG format. Such files generally have the extension .mpg. See also JPEG. Compare Motion JPEG.

MPEG–1  n. The original MPEG standard for storing and retrieving video and audio information, designed for CD–ROM technology. MPEG–1 defines a medium bandwidth of up to 1.5 Mbps, two audio channels, and noninterlaced video. See also MPEG (definition 1). Compare MPEG–2, MPEG–3, MPEG–4.

MPEG–2  n. An extension of the MPEG–1 standard designed for broadcast television, including HDTV. MPEG–2 defines a higher bandwidth of up to 40 Mbps, five audio channels, a wider range of frame sizes, and interlaced video. See also MPEG (definition 1). Compare MPEG–1, MPEG–3, MPEG–4.

MPEG–3  n. Initially an MPEG standard designed for HDTV (high–definition television), but it was found that MPEG–2 could be used instead. Therefore, this standard no longer exists. See also MPEG (definition 1). Compare MP3, MPEG–1, MPEG–2, MPEG–4.

MPEG–4  n. A standard currently under development designed for videophones and multimedia applications. MPEG–4 provides a lower bandwidth of up to 64 Kbps. See also MPEG (definition 1). Compare MPEG–1, MPEG–2, MPEG–3.

multimedia  n. The combination of sound, graphics, animation, and video. In the world of computers, multimedia is a subset of hypermedia, which combines the aforementioned elements with hypertext. See also hypermedia.

multiple recipients  n.  1. The capability of sending e–mail and instant messages to more than one user at a time by listing more than one e–mail address on a line. Delimiters such as commas or semicolons are used to separate the e–mail addresses. 2. The subscribers on a mailing list. A message sent to the list is addressed to the "multiple recipients of" the list.


N

.NET Messenger Service  n. A popular instant–messaging service provided by Microsoft as part of the .NET strategy. With .NET Messenger Service, formerly called MSN Messenger Service, users can communicate using the Windows Messenger, included in Windows XP, or MSN Messenger applications. See also instant messaging. Compare ICQ.

netcasting  n.  1. Synonym for webcasting.

netiquette  n. Short for network etiquette. Principles of courtesy observed in sending electronic messages, such as e–mail, instant messages, and Usenet postings. The consequences of violating netiquette include being flamed and having one's name placed in the bozo filter of one's intended audience. Disapproved behavior includes gratuitous personal insults; posting of large amounts of irrelevant material; giving away the plot of a movie, television show, or novel without warning; posting offensive material without encrypting it; and excessive cross–posting of a message to multiple groups without regard to whether the group members are likely to find it interesting. See also flame2.

Netspeak  n. The set of conventions for writing English in e–mail, instant messages, IRCs, and newsgroups. Netspeak is characterized by acronyms (such as IMHO or ROFL) and clarifying devices such as emotags and emoticons. Use of Netspeak should be governed by netiquette. See also emotag, emoticon, netiquette.


O

opacity  n. The quality that defines how much light passes through an object's pixels. If an object is 100 percent opaque, no light passes through it.

optical scanner  n. An input device that uses light–sensing equipment to scan paper or another medium, translating the pattern of light and dark or color into a digital signal that can be manipulated by either optical character recognition software or graphics software. Scanners have different methods for holding the input medium, including flatbed, whereby the medium is held on a piece of glass; sheet–fed, whereby sheets of paper are pulled over a stationary scanning mechanism; handheld, whereby the user moves the device over the document to be scanned; and overhead, whereby the document is placed face up on a stationary bed below a small tower, which moves across the page.

optimize  vb.  1. In Web design functions, to reduce the file size of a photo or graphic to allow faster loading. Files are typically optimized through a combination of means such as reducing overall image quality and fine–tuning color information.

overlay2  vb.  1. In computer graphics, to superimpose one graphic image over another. 2. In video, to superimpose a graphic image generated on a computer over video signals, either live or recorded.

overprint  vb. The process of printing an element of one color over one of another color without removing, or knocking out, the material underneath. Compare knockout (definition 1).


P

paintbrush  n. An artist's tool in a paint program or another graphics application for applying a streak of solid color to an image. The user can usually select the width of the streak. Compare spraycan.

palette  n.  1. In paint programs, a collection of drawing tools, such as patterns, colors, brush shapes, and different line widths, from which the user can choose. 2. A subset of the color look–up table that establishes the colors that can be displayed on the screen at a particular time. The number of colors in a palette is determined by the number of bits used to represent a pixel. See also color look–up table, pixel.

PCI card  n. Short for Peripheral Component Interconnect card. A card that fits into a PCI local bus to add functionality to a PC. Examples of the types of PCI cards available include TV tuner cards, video adapters, and network interface cards.

peripheral  n. In computing, a device, such as a disk drive, printer, modem, or joystick, that is connected to a computer and is controlled by the computer's microprocessor.

photo editor  n. A graphics application used to manipulate an image, such as a scanned photograph, digitally.

photorealism  n. The process of creating images that are as close to photographic or "real–life" quality as possible. In computer graphics, photorealism requires powerful computers and highly sophisticated software and is heavily mathematical.

pixel  n. Short for picture (pix) element. One spot in a rectilinear grid of thousands of such spots that are individually "painted" to form an image produced on the screen by a computer or on paper by a printer. A pixel is the smallest element that display or print hardware and software can manipulate in creating letters, numbers, or graphics.

pixel image  n. The representation of a color graphic in a computer's memory. A pixel image is similar to a bit image, which also describes a screen graphic, but a pixel image has an added dimension, sometimes called depth, that describes the number of bits in memory assigned to each on–screen pixel.

pixel map  n. A data structure that describes the pixel image of a graphic, including such features as color, image, resolution, dimensions, storage format, and number of bits used to describe each pixel. See also pixel, pixel image.

player  n. In relation to digital audio, a program that plays music and other audio files that have been ripped (transferred from a compact disc to a hard disk) and then encoded in a playable format, such as MP3. See also encoder, MP3, ripper.

PNG  n. Acronym for P ortable Network Graphics. A file format for bitmapped graphic images, designed to be a replacement for the GIF format, without the legal restrictions associated with GIF. See also GIF.

presence technology  n. An application, such as instant messaging, which finds specific users when they are connected to the network and which may alert interested users to each other's presence. Third–generation wireless networks will integrate presence technology with digital cell phones, PDAs, pagers, and other communications and entertainment devices.

presentation broadcast  n. A PowerPoint feature that allows you to run a presentation over the Web. The presentation is saved in HTML format and can contain audio and video. It can also be recorded and saved to be viewed later.

printer  n. A computer peripheral that puts text or a computer–generated image on paper or on another medium, such as a transparency film. Printers can be categorized in any of several ways: impact versus nonimpact; print technology; character formation; method of transmission; method of printing; print capability; and print quality. Impact versus nonimpact The most common distinction is impact versus nonimpact. Impact printers physically strike the paper and are exemplified by pin dot–matrix printers and daisy–wheel printers; nonimpact printers include every other type of print mechanism, including laser, ink–jet, and thermal printers. Print technology Chief among types of print technology are pin dot–matrix, ink–jet, laser, thermal, and (although somewhat outdated) daisy–wheel or thimble printers. Pin dot–matrix printers can be further classified by the number of pins in the print head: 9, 18, 24, and so on. Character formation Fully formed characters made of continuous lines (such as those produced by a daisy–wheel printer) versus dot–matrix characters composed of patterns of dots (such as those produced by standard dot–matrix, ink–jet, and thermal printers). Laser printers, while technically dot–matrix, are generally considered to produce fully formed characters because their output is very clear and the dots are extremely small and closely spaced. Method of transmission Parallel (byte–by–byte transmission) versus serial (bit–by–bit transmission). These categories refer to the means by which output is sent to the printer rather than to any mechanical distinctions. Many printers are available in either parallel or serial versions, and still other printers offer both choices, yielding greater flexibility in installation options. Method of printing Character by character, line by line, or page by page. Character printers include standard dot–matrix, ink–jet, thermal, and daisy–wheel printers. Line printers include the band, chain, and drum printers that are commonly associated with large computer installations or networks. Page printers include the electrophotographic printers, such as laser printers. Print capability Text–only versus text–and–graphics. Text–only printers, including most daisy–wheel and thimble printers and some dot–matrix and laser printers, can reproduce only characters for which they have matching patterns, such as embossed type or internal character maps. Text–and–graphics printers—dot–matrix, ink–jet, laser, and others—can reproduce all manner of images by "drawing" each as a pattern of dots. Print quality Draft versus near–letter quality versus letter quality.

privacy  n. The concept that a user's data, such as stored files and e–mail, is not to be examined by anyone else without that user's permission. A right to privacy is not generally recognized on the Internet. Federal law protects only e–mail in transit or in temporary storage, and only against access by Federal agencies. Employers often claim a right to inspect any data on their systems. To obtain privacy, the user must take active measures such as encryption.

process color  n. A method of handling color in a document in which each block of color is separated into its subtractive primary color components for printing: cyan, magenta, and yellow (as well as black). All other colors are created by blending layers of various sizes of halftone spots printed in cyan, magenta, and yellow to create the image. See also color model, color separation (definition 1). Compare spot color.

progressive JPEG  n. An enhancement to the JPEG graphics file format that gradually displays a photo–realistic picture in a Web browser, showing increasingly detailed versions of the picture until the entire file has finished downloading.

pseudo–streaming  n. A method used for real–time display of audio and video over the Web. Unlike sound or video files that are downloaded to a computer in their entirety before they can be played back, pseudo–streaming enables playback after only a portion of the file—enough to fill a buffer on the receiving computer—has been downloaded. Pseudo–streaming, unlike "true," or Web, streaming, does not depend on server software to dynamically monitor the transmission. It can, however, play back only from the beginning of the file, rather than from any point, as can be the case with true streaming. See also stream.

publishing point  n. A publishing point is a virtual directory used for storing content or delivering a live stream. End users reach a publishing point through its URL. There are two types of unicast publishing points: on–demand for stored content and broadcast for live streams.


R

raster image processor  n. A device, consisting of hardware and software, that converts vector graphics or text into a raster (bitmapped) image. Raster image processors are used in page printers, phototypesetters, and electrostatic plotters. They compute the brightness and color value of each pixel on the page so that the resulting pattern of pixels re–creates the vector graphics and text originally described. Acronym: RIP.

RCA connector  n. A connector used for attaching audio and video devices, such as stereo equipment or a composite video monitor, to a computer's video adapter.

reallysafe palette  n. A color look–up table (CLUT) consisting of 22 colors from the 216–color websafe palette that are completely consistent when viewed with all Web browsers on all major computer platforms. The reallysafe palette arose from an experiment that indicated that most of the colors of the websafe palette shift to some degree in different viewing environments. See also browser CLUT, websafe palette.

real–time streaming  n. The process of delivering a streaming media file via a specialized streaming media server using real–time streaming protocol (RTSP). With real–time streaming, the file itself actually plays on the streaming media server, even though it is viewed on the computer that opened the file. Real–time streaming transmits at a higher bandwidth than HTTP streaming. It is often used to broadcast live events, such as concerts or keynote conference addresses. See also HTTP streaming.

region code  n. Codes on DVD movie titles and DVD–ROM drives that prevent playback of certain DVDs in certain geographical regions. Region codes are part of the DVD specification.

resolution  n.  1. The fineness of detail attained by a printer or a monitor in producing an image. For printers that form characters from small, closely spaced dots, resolution is measured in dots per inch, or dpi, and ranges from about 125 dpi for low–quality dot–matrix printers to about 600 dpi for some laser and ink–jet printers (typesetting equipment can print at resolutions of over 1000 dpi). For a video display, the number of pixels is determined by the graphics mode and video adapter, but the size of the display depends on the size and adjustment of the monitor; hence the resolution of a video display is taken as the total number of pixels displayed horizontally and vertically. See also high resolution, low resolution. 2. The process of translation between a domain name address and an IP address.

rewritable digital video disc  n. Technology for recording data on disks that have the same storage capacity as digital video discs (DVDs) but can be rewritten like the compact disc–rewritable (CD–RW) devices. See also digital video disc.

RGB  n. Acronym for red–green–blue. A model for describing colors that are produced by emitting light, as on a video monitor, rather than by absorbing it, as with ink on paper. The three kinds of cone cells in the eye respond to red, green, and blue light, respectively, so percentages of these additive primary colors can be mixed to get the appearance of any desired color. Adding no color produces black; adding 100 percent of all three colors results in white. See also CMYK, RGB monitor. Compare CMY.

RGB display  n. See RGB monitor.

RGB monitor  n. A color monitor that receives its signals for red, green, and blue levels over separate lines. An RGB monitor generally produces sharper and cleaner images than those produced by a composite monitor, which receives levels for all three colors over a single line. See also RGB. Compare composite video display.

rip  vb. To convert audio data from a compact disc into a WAV file or other digital format, typically in preparation for further encoding as an MP3 file. See also MP3.

ripper  n. Digital audio technology that converts audio data from a compact disc into a WAV file or other digital format. An encoder then converts this file into a file (typically an MP3 file) that can be played back by software known as a player. See also encoder, MP3.


S

SAOL  n. Acronym for Structured Audio Orchestra Language. Part of the MPEG–4 standard, SAOL describes a set of tools for producing computer music, audio for computer games, streaming Internet sound or music, and other multimedia applications. SAOL is a flexible computer language for describing music synthesis and integrating synthetic sound with recorded sound in an MPEG–4 bit stream. See also MPEG–4, streaming (definition 1).

scan  vb.  1. In television and computer display technologies, to move an electron beam across the inner surface of the screen, one line at a time, to light the phosphors that create a displayed image. 2. In facsimile and other optical technologies, to move a light–sensitive device across an image–bearing surface such as a page of text, converting the light and dark areas on the surface to binary digits that can be interpreted by a computer.

scan head  n. An optical device found in scanners and fax machines that moves across the subject being scanned, converts light and dark areas to electrical signals, and sends those signals to the scanning system for processing.

scanner  n. An optical input device that uses light–sensing equipment to capture an image on paper or some other subject. The image is translated into a digital signal that can then be manipulated by optical character recognition (OCR) software or graphics software. Scanners come in a number of types, including flatbed (scan head passes over a stationary subject), feed (subject is pulled across a stationary scan head), drum (subject is rotated around a stationary scan head), and handheld (user passes device over a stationary subject).

Secure Digital Music Initiative  n. A coalition of companies from the recording, electronics, and information technology industries founded in February 1999 for the purpose of developing an open standard for the secure distribution of music in digital form. The Secure Digital Music Initiative specification is designed to provide consumers with flexibility and convenient access to electronically distributed music (that is, over the Internet) while also protecting the rights of artists. Acronym: SDMI. See also MP3, Windows Media Technologies.

sheet–fed scanner  n. A scanner with a single–sheet feed mechanism, in which sheets of paper are pulled in by the scanner and scanned as they pass over a stationary scanning mechanism. Sheet–fed scanners allow for automatic scanning of multiple–sheet documents. See also scanner. Compare drum scanner, flatbed scanner, handheld scanner.

shout  vb. To use ALL CAPITAL LETTERS for emphasis in e–mail, instant messages, or a newsgroup article. Excessive shouting is considered a violation of netiquette. A word can be more acceptably emphasized by placing it between *asterisks* or _underscores_. See also netiquette.

skin  n. An alternative graphical interface for an operating system (OS) or a software program. A skin customizes the look of the OS or program but does not affect its functionality. Programs that allow the use of skins usually make standards available for the creation and distribution of new skins.

skin mode  n. An operational state of various media players, including RealPlayer, Winamp, and Windows Media Player, in which the user interface is customized and displayed as a skin. Often some features of the player are not accessible in skin mode. Skin mode was called compact mode in Windows Media Player 7.

smiley  n.  See emoticon.

sound buffer  n. A region of memory used to store the bit image of a sequence of sounds to be sent to a computer's speaker(s).

sound card  n. A type of expansion board on PC–compatible computers that allows the playback and recording of sound, such as from a WAV or MIDI file or a music CD–ROM. Most PCs sold at retail include a sound card. Also called: sound board. See also MIDI.

sound clip  n. A file that contains a short audio item, usually an excerpt from a longer recording.

sound editor  n. A program that allows the user to create and manipulate sound files.

spatial digitizer  n. A three–dimensional scanner most often used in medical and geographical work. Compare optical scanner.

spot color  n. A method of handling color in a document in which a particular color of ink is specified and each page having elements in that color is printed as a separate layer. The printer then prints one layer for each spot color in the document. See also color model, color separation (definition 1). Compare process color.

spraycan  n. An artist's tool in Paintbrush or another graphics application for applying a pattern of dots to an image.

stream1  n. Any data transmission, such as the movement of a file between disk and memory, that occurs in a continuous flow. Manipulating a data stream is a programming task. Consumers, however, are likely to encounter references to streams and streaming in connection to the Internet, which has increased reliance on stream techniques to enable users (even those with slower equipment) to access large multimedia files—especially those containing audio and video components—and to display or play them before all the data has been transferred.

stream2  vb. To transfer data continuously, beginning to end, in a steady flow. Many aspects of computing rely on the ability to stream data: file input and output, for example, and communications. If necessary, an application receiving a stream must be able to save the information to a buffer in order to prevent loss of data. On the Internet, streaming enables users to begin accessing and using a file before it has been transmitted in its entirety.

stream cipher  n. A method for encrypting a data sequence of unlimited length using a key of fixed length.

streaming  n.  1. On the Internet, the process of delivering information, especially multimedia sound or video, in a steady flow that the recipient can access as the file is being transmitted. 2. In magnetic tape storage devices, a low–cost technique to control the motion of the tape by removing tape buffers. Although streaming tape compromises start/stop performance, it achieves highly reliable storage and retrieval of data, and is useful when a steady supply of data is required by a particular application or computer.

streaming buffer  n. A small sound buffer that can play lengthy sounds because the application dynamically loads audio data into the buffer as it plays. For example, an application could use a buffer that can hold 3 seconds of audio data to play a 2–minute sound. A streaming buffer requires much less memory than a static buffer.

SVGA  n. Acronym for Super Video Graphics Array. A video standard established by the Video Electronics Standards Association (VESA) in 1989 to provide high–resolution color display on IBM–compatible computers. Although SVGA is a standard, compatibility problems can occur with the video BIOS.


T

Tagged Image File Format  n. See TIFF.

tessellate  vb. To break an image into small, square regions for processing or output.

three–point editing  n. In digital video editing, a feature that simplifies the process of placing new video within a sequence by assisting in calculating edit points. To make an edit, in and out points must be defined in the video clip to be added and in the sequence into which the clip is to be inserted. The user provides any three of these edit points and the editing software determines the fourth.

.tif or .tiff  n. The file extension that identifies bitmap images in Tagged Image File Format (TIFF). See also TIFF.

TIFF or TIF  n. Acronym for Tagged Image File F ormat or Tag Image File F ormat. A standard file format commonly used for scanning, storage, and interchange of gray–scale graphic images. TIFF may be the only format available for older programs (such as older versions of MacPaint), but most modern programs are able to save images in a variety of other formats, such as GIF or JPEG. See also gray scale. Compare GIF, JPEG.

TIFF JPEG  n. Acronym for Tagged Image File F ormat JPEG. A means of saving photographic images compressed according to the JPEG (Joint Photographic Experts Group) standard. TIFF JPEG saves more information about an image than does the lower–end JFIF (JPEG File Interchange Format), but TIFF JPEG files are limited in portability because of differences in implementation among applications. See also JFIF, JPEG.

tone compression  n. In digital graphics, the compression of the complete color range of an image to the narrower range of the chosen output device. Allowing for tone compression in scanning and graphics editing may improve the quality of the final printed image.

true color  n. See 24–bit color.


U

uncompress  vb. To restore the contents of a compressed file to its original form. Also called: decompress. Compare compress.


V

video  adj. Of or pertaining to the visual component of a television signal. In relation to computers, video refers to the rendering of text and graphics images on displays.

video adapter  n. The electronic components that generate the video signal sent through a cable to a video display. The video adapter is usually located on the computer's main system board or on an expansion board, but it is sometimes built into the terminal. Also called:video adapter board, video board, video card, video controller, video display adapter.

video adapter board  n. See video adapter.

video board  n. See video adapter.

video buffer  n. The memory on a video adapter that is used to store data to be shown on the display. When the video adapter is in a character mode, this data is in the form of ASCII character and attribute codes; when it is in a graphics mode, the data defines each pixel. See also bit image, pixel image.

video capture board  n. See video capture device.

video capture card  n. See video capture device.

video capture device  n. An expansion board that converts analog video signals to digital form and stores them in a computer's hard disk or other mass storage device. Some video capture devices are also capable of converting digital video to analog video for use in a VCR. Also called: video capture board, video capture card.

video card  n. See video adapter.

video clip  n. A file that contains a short video item, usually an excerpt from a longer recording.

video compression  n. Reduction of the size of files containing video images stored in digital form. If no compression were done, 24–bit color video at 640 x 480 pixels would occupy almost one megabyte per frame, or over a gigabyte per minute. Video compression can, however, be lossy without affecting the perceived quality of the image. See also lossy compression, Motion JPEG, MPEG.

video conferencing  n. Teleconferencing in which video images are transmitted among the various geographically separated participants in a meeting. Originally done using analog video and satellite links, today video conferencing uses compressed digital images transmitted over wide area networks or the Internet. A 56K communications channel supports freeze–frame video; with a 1.544–Mbps (T1) channel, full–motion video can be used. See also freeze–frame video, full–motion video.

video controller  n. See video adapter.