Computer & Image Glossary

Accelerated graphics port(AGP) : An advanced graphics card interface enabling super-fast 30 visuals.

Authoring package : A program used to create web pages.

Backup : A second safe copy of a file, letter or data.

BIOS : The BIOS controls the basic features of a PC and tells the operating system things like time, date, and the size of your hard drive.

Bit : A one-kilobyte (1Kb) file consists of 1,024 bytes, which each consists of 8 bits. One kilobyte (1Kb) equals 8,192 bits. One megabyte (1Mb) is 1,024 kilobytes

Bitmap Graphic : image made up of pixels (or tiny dots).

Bookmark : Word or picture 'marked' so you can jump to it by name from within a bookmark list.

Browser : Software program developed for navigating the net.

Cache : A special type of memory that speeds up all manner of operations.

CD-ROM Drive : Used for installing software - on CD-ROM discs - and playing multimedia audio and video.

CD-ROM : You will be familiar with CDs from your record collection, but CDs can store a lot more than just music. This small plastic disc can bold up to 650Mb of data. In the computer world, the same type of disc is used to store files and is known as CD-ROM.[Compact Disc-Read Only Memory]

Cells : Spreadsheets are divided into cells and each cell has a unique name to help you navigate around. For example, the first cell is called A1 because it occupies the first row of the first column.

Chat rooms : A bit like the premium rate chat lines you see advertised on late night TV, although most won't cost you an arm and a leg to join.

Clipart : A library of drawings or photographs that you can use on your web page or in your documents.

Control Panel : This is a collection of icons that allow you to configure the basic functions of Windows and your PC. Within the Control Panel there are icons to define fonts, background colours, printer use and a whole host of other options.

Cut : Just like it sounds: if you want to move an item, for example text, entirely from one document and place it in another, this function will delete the text but save a copy of it for you to use later on.

Cyberspace : A term coined by William Gibson meaning the world 'inside' computers.

Database : A kind of PC filing cabinet for data with powerful searching capabilities.

Default Printer : If you have more than one printer connected to your PC, this is the printer that your PC will automatically choose to printout documents on.

Dialog box : A small window that is displayed in Windows. A dialog box is normally used to display a message, which could be a warning, from the program to the user.

Digital camera : A camera that takes images digitally and stores them in its own memory, as opposed to the light sensitive film used in traditional cameras.

Disk Defragmenter or defrag : Utility that reorganises (defragments) flies and parts of files on your hard disk- puts fragmented files back together (see Fragmentation).

DOS Disk Operating System : The standard operating system before the dawn of Windows. DOS manages how files are stored on your PC.It is controlled through typed commands.

Dots Per Inch (DPI) : The way resolution of scanned and printed images is measured. Both types of picture are made up of tiny dots.

Download : To obtain a file from a website, usually by clicking a word or icon on the web page.

Driver : Software to enable you're a hardware peripheral to function in Windows.

DVD : Stands for Digital Versatile Disc. This new medium can store huge amounts of data on one disc that looks just like a CD, including films, with excellent quality sound and pictures.

E-commerce : The word given to selling goods and services over the internet.

Email : Short for electronic mail, the system of sending notes and memos between computers via a modem and phone line.

Events : An action in Windows, such as opening a document, emptying the Recycle Bin, or shutting down your PC.

Expansion slots : Electrical connector fitted to the motherboard that lets an expansion card plug into to the computer.

File Extension : The suffix - that's the letters after the dot - in a file's name. Examples include .doc (for a word document) and .xis (Excel) and .txt (Notepad). This is how Windows knows which application to use to open a particular file.

Find Files : Utility for finding files anywhere on your hard disk or network. Can be accessed within Windows Explorer or by right-clicking on the My Computer icon on your PC desktop.

Font : A collection of characters with predefined styles and sizes - such as Courier or Times New' Roman.

Force feedback joystick : A joystick that provides force and movement, such as vibration and pull. Gives you the sensation of firing a machine, divebombing a plane, and so on.

Fragmentation : When there's not enough room to save a file in one physical location on your hard disk: the file will be spread over several smaller locations. This is an inevitable consequence of constantly saving and deleting files.

Gigabyte (Gb) : A thousand megabytes.

Graphics card : The part of a PC that controls the screen's image. Most PCs are fitted with 2D cards as standard - which is all Windows 95 needs - bet many new games require a 3D graphics card as well.

Hard disk : A high-capacity storage device that a PC uses for programs and data, measured in gigabytes. Information held on a hard disk is safe when the power is withdrawn.

Hardware : Your computer set up is split into two parts, hardware and software. Software covers the programs that run on your machine, such as Windows 95, Word for Windows, games and suchlike. Hardware is the computer itself and peripherals as such the printer and scanner.

Home page : The first page that visitors to a website see.

HPC : Stands for Handheld Personal Computer, coined by Microsoft for a hand held computer that runs Windows CE.

HTML : Hypertext mark-up language - used to create pages for the world wide web.

Hyperlink : Link which lets you jump between words, objects, or documents.

IAP/ISP : Internet Access Providers or Internet Service Providers are the companies, such as Compuserve or Demon, which sell you access to the Net. IAPs tend-to provide a basic link, ISPs additional services and content.

Inkjet Printer : A light, quiet and relatively cheap printer that produces pages by squirting a stream of tiny drops of electrically charged ink at the surface of the paper.

Interface : 1)The look and feel of a program such as buttons and windows.
2) A physical "dongle" or add-on that allows changes of data to take place.

Interlaced : Monitors draw an image every other line, before the monitor goes back to the top and fills in the lines missed. Can result in flickery images.

Internet : An international network that links thousands of computers, using telephone and cable links.

Internet Explorer : One of the two most popular browsers, published by Microsoft.

IP : Internet protocol: a 32bit number which identifies precisely the position of a computer on the internet.

IRQ and I/O address : Settings which determine the memory addresses and processor usage for PC add-in cards. You shouldn't change these unless you really know what you are doing.

ISA : 'Industry standard' slots inside your PC for connecting modems, soundcards and other add-ins. ISA slots have been superseded by higher-performance PCI slots, but all PCs include at least some for the sake of compatibility with older add-ins.

ISDN : A hyper-fast digital telephone line.

Joystick : A device that lets you control movement in games, etc.

JPEG : Is a standard for storing pictures in a compressed format, so they take up less disk space.

K56flex : The 56K modem technology developed by Lucent Technologies. Though incompatible with x2, K56flex modems are made by a number of other manufacturers.

Kbps : Kilobits per second - another measure of modem speed. A kilobit is 1,000 bits.

Laser printer : A printer that produces very high quality text and graphics using a laser beam.

Launch : To start up a program, such as Microsoft Word or Excel, by clicking on its icon or selecting it from the Windows Start menu.

LCD (Liquid Crystal Display) : Used by manufacturers in notebook computers, and for making desktop monitors.

Li-ion Lithium Ion : The most sophisticated type of rechargeable battery, light, long life with virtually no memory effect. Unfortunately expensive and reserved for high-end phones only.

Mail Merge : A feature in a word processor that lets you prepare and then send the same letter to lots of different people without having to keep re-typing it.

Media : Material you print on, such as paper and envelopes.

Megabyte (Mb) : A measurement of storage space. It roughly translates to a million characters of text, or 180,000 words, enough for a good- sized novel.

Memory (RAM) : Random Access Memory: the computer's temporary storage area, measured in megabytes (Mb). Anything written to memory will be lost when the power is switched off.

MHz : Stands for megahertz. A measure of the frequency of a timing signal that's equal to 1,000,000 cycles per second. A measure of how fast the processor in your PC works.

MIDI : Stands for Musical Instrument Digital Interface. It is a connector on a sound card which allows your computer to control musical instruments, such as keyboards.

Millennium bug : The problem that arises when computers cannot recognise the date changeover from the last two digits of 1999 to the year 2000.

Modem : A device that converts electronic signals from your PC into sound signals that can be transmitted over a phone line.

Motherboard : The main circuit board in your computer.

My Computer : Usually you will find an icon labelled 'My Computer' in the top left corner of your Windows desktop. Double-click on this and a Window will appear, containing icons for any disk drives you have connected to your PC, as well as any printers you have installed.

Network computer : A special type of computer that relies on the Internet for all activities and operations. If you want to launch a program on a network computer it must first be downloaded over the internet.

Newsgroups : One of the features of the internet. They are like free-for-all discussion forums.

NiCad : Heavy, cheap and basic type of rechargeable battery.

NiMH Nickel Metal Hybrid : A more sophisticated rechargeable battery capable of lasting longer.

Non-interlaced : Where monitors draw an entire image line by line, resulting in a much steadier image.

Notebook : Small portable computer which, while it will have the features of a desktop PC, usually has an LCD screen and is roughly the size of an A4 notepad.

Online banking : Using your PC to conduct your account direct with your bank, via a modem.

Operating System : The software that controls the actions of the different parts of your PC. In older PCs, the operating system is called MS-DOS. In modern PCs it is Windows 95 that manages the screen, keyboard disks and printers.

Parallel port : Socket at the back of your PC for connecting to a printer. It sends data to the printer over eight parallel wires.

PC Card : A credit card-sized device, such as a modem, designed for use on notebook and handheld computers.

PCI : PC expansion connector, similar to ISA but much improved.

PDA : Stands for Personal Digital Assistant, a generic term for any small, electronic personal organiser.

Pentium : A processor developed by Intel and used in high-performance PCs. It replaced the older 80486 chip and is compatible with all the older 80x86 processor range.

Pentium II : An improved version of Intel's original Pentium processor, which powers millions of PCs around the world.

Pentium MMX : An enhanced version of Intel's standard Pentium processor. The MMX part stands loosely for MultiMedia eXtensions, which means the chip is geared up to handle all sorts of multimedia-intensive tasks such as playing videos and music.

Pixel : The smallest point in your image. Image resolution is measured in the number of pixels or points vertically and horizontally.

Plug and Play : Plug and Play compliant add-in cards or peripherals are automatically detected and configured when they are connected to your PC.

Plug-Ins : Additional features in the form of small programs which can be downloaded from the internet.

Processor/CPU (central processing unit) : Heart of the computer. It does most of the hard work and the faster the processor, the better the system is likely to be.

Pt or point size : Often abbreviated to 'pt' this is the measurement typographers use to describe the size of text.

QWERTY keyboard : So-called because the first six letters on the top row read 'QWERTY'.

RAM or Random Access Memory : It's the memory of your computer, which is measured in megabytes (Mb).

Removable Storage Device : Disk drives that use high-capacity disks which can be removed and stored remotely. Typical examples include lomega's Jaz and the Syjet from SyQuest.

Resolution : The number of picture pixels that are displayed on the screen, or points per inch for a printer. The more pixels, the sharper the image.

RGB image : A colour picture made up where each pixel is represented by three numbers for the red, green and blue pixel values. An RGB image is made from three greyscale channels.

Right-click : Most actions in Windows are performed by clicking the left mouse button. However, since the arrival of Windows 95, many programs - and Windows itself - make use of the right mouse button click to display a pop-up menu with special functions.

ROM : Acronym for Read Only Memory. Any memory that can be read but not written to, such as CD-ROM.

Sample : A Sound bite stored as digital data on your PC.

Scandisk : Software utility that check for hard disk faults. Comes with Windows 95.

Scanner : A device that can convert photos and text to an electronic format that can be manipulated on your PC.

Screen saver : Software which, after period of inactivity, replaces the existing image on screen and displays moving objects to protect the screen.

Scroll/scrollbar : When a list of items - file names, fonts, etc - is too long to display in a window you can scroll up or down the list by clicking on the Windows' 'scrollbar' - also called the vertical scrollbar.

SCSI : Stands for Small Computer Systems Interface. A standard high-speed parallel interface used to connect PCs to peripheral devices such as disk drives and scanners.

Search Engine : An online service which take the strain out of surfing the web by asking you for keywords and then providing a list of websites that contain your chosen words.

Serial port : A connector at the hack of a PC that can connect devices, such as modems and palmtops.

Shareware : Sample software which is available free. It you keep it, however, you then have to pay the author.

Shortcut : A 'fast-launch' link to your document or application in the form of a desktop icon.

SIMM slots : Single In-line Memory Module slots. SIMM slots allow you to expand your machine by adding extra memory. DIMMs are simply Dual In-line Memory Modules.

Simulations : Games that simulate real life, the most popular are flight simulators.

Software Application : Any program or group of programs which tells hardware how it should perform, including operating system, word processors and applications programs.

Spam : The term given to junk email.

Spreadsheet : A kind of super-calculator useful for analysing any collection of figures, from a family budget, to a car loan, a lease, or an investment.

Strategy game : A strategy game involves multiple characters or elements, with multiple goals, such as a war game where you must win battles using troops, tanks and aircraft.

Surfing : Popular metaphor used for describing someone exploring the World Wide Web.

Surround-sound : An arrangement of audio equipment which gives cinema quality sound.

Swapfile : An area of hard disk space that your PC can use as 'virtual' memory, or RAM.

System Tools menu : This folder can be found by clicking the Windows 95 Start button, then looking within Programs/Accessories. In it you will find all the utilities you need for maintaining and troubleshooting your copy of Windows.

Tab : Dialog boxes often combine settings for different associated functions. Each 'page' of settings is separated by a tab.

Taskbar : A bar that normally runs along the bottom of the screen in Windows 95 and displays the Start button and a list of other programs or windows that are currently active.

TCP/IP : Transmission control protocol/internet protocol: the protocol used to transfer data and information from one internet connected computer to another.

TFT : Thin film transistor technology used to deliver high-quality images on laptop monitors.

TIF : Tagged Image File format A standard file format used to store graphic images, including black and white and colour.

Toner : Basically, the 'ink' used in a laser printer - it's just the same as the toner in a photocopier.

Toolbar : A window that contains a range of icons that allows you to access different tools.

Toolbox : The software equivalent of a mechanic's toolkit. An program's toolbox should contain everything necessary to complete the task in hand. In an image-editing application, the toolbox will have a selection of drawing, colouring and editing tools.

Touchpad : A small, touch-sensitive pad, which acts as an alternative to a mouse on some palmtop PCs.

Tower : A computer system unit which stands upright.

TWAIN : A standard way for scanners and some other devices to talk to you computer. It stands for Technology Without An Important Name!

Typeface : Sometimes called fonts, there are thousands of different typefaces available.

Undo : Most programs let you get out of trouble by undoing the last action you've performed.

Upgrade : To improve the performance or specification of your computer by adding more memory, a larger hard disk or another improvement. Software can also upgraded.

URL : Universal Resource Locator. Usually starting http or www this is the website's address.

USB connectors : Universal Serial Bus connectors are a recent standard for connecting peripherals, such as scanners and printers to PCs quickly and simply.

Virtual memory : Part of the space on your hard disk - this reserved space is called the swap disk - can be configured to act as if it were RAM memory whenever more system memory is called for.

Voicemail : An answerphone service which records callers' messages.

Wave File (.wav) Windows' audio file format used for saving and loading sounds to and from disc.

Web : Part of the internet that you can explore using a web browser.

Windows 98 : Current version of the Windows operating system software.

Windows Explorer : Windows Explorer is where you can browse through your files and folders.

Windows NT : A more advanced version of Microsoft's Windows 95/98 used primarily in a business environment.

Wizard : A specific step-by-step help guide that will help you perform a task, such as making a template.

Word processor : A software application for preparing documents.

Worksheet Excel itself is a spreadsheet, but the individual screens of rows and columns that you work with are called worksheets.

World Wide Web (WWW): The 'web' is a collection of online documents housed on net servers worldwide.

Y2K : Short for year 2000.

Zip drive: A high-capacity disk drive designed by lomega, capable of storing 100Mb of information on sturdy pocket-sized disks.

Aperture : The opening in a camera lens that can be adjusted to control the amount of light entering the camera.

Banding : The presence of extraneous lines in a printed page. Banding generally occurs when an inkjet printer needs to pass the print head over a page multiple times to print each colour.If the page isn't exactly lined up for each pass, lines may appear.

Bit : Short for binary digit, the smallest unit of information a computer can read. A single bit can hold only one of two values: 0 or 1, More meaningful information is obtained by combining consecutive bits into larger units. For example, a byte is composed of eight consecutive bits. Graphics are also often described by the number of bits used to represent each dot. A one bit image is pure black or white; an eight-bit image supports 256 colours or greyscales; and a 24- or 32-bit graphic supports True Colour that is 16.7 million colours. Bit depth The number of bits used to represent the colour of each dot - or pixel - on the screen.

Bit depth : Is also referred to as colour depth or pixel depth. Bit depth determines the number of colours that can be displayed at one time. Digital video requires at least 15 bits, while 24 bits produces photo-realistic colours.

Bitmap : A representation, consisting of rows and columns of dots, of a graphics image in computer memory. The value of each dot - whether it is filled in or not - is stored in one or more bits of data. For pure black or white images,one bit is sufficient to represent each dot, but for colours and shades of grey, each dot requires more than one bit of data.The more bits used to represent a dot, the more colours and shades of grey that can be represented. The density of the dots, known as the resolution, determines how sharply the image is represented. This is often expressed in dots per inch (dpi) or simply by the number of rows and columns, such as 640x480.

Colour depth : The number of distinct colours that can be represented by a piece of hardware or software. Colour depth is sometimes referred to as bit depth because it is directly related to the number of bits used for each pixel. A 24-bit graphics card, for example, has a colour depth of two to the 24th power- about 16.7 million colours.

CMYK : Short for Cyan-Magenta-Yellow-BlacK, and pronounced as separate letters. CMYK is a colour model in which all colours are described as a mixture of these four process colours. CMYK is the standard colour model used in printing for fullcolour documents. Because such printing uses inks of these four basic colours, this process is often called four-colour printing. In contrast, display devices generally use a different colour model called RGB, which stands for Red-Green-Blue. One of the most difficult aspects of desktop publishing in colour is colour matching - the process of converting RGB colours into CMYK colours so that printed matter looks the same as the screen image.

Continuous Tones : Refers to images that have a virtually unlimited range of colour or shades of grey. Photographs and television images, for example, are continuous-tone images. Converting a black-and-white continuous tone image into a computer image is known as grey scaling.

Download : This is the process of transferring files onto your PC. These could be from the internet or picture files stored on a digital camera, for example.

DPI : Stands for dots per inch. This is the way the resolution of scanned and printed images is measured. Both types of picture are made up of individual tiny dots. The more dots there are per inch, the smaller they are, and so the better the image.

Email : Short for electronic mail, the system of sending notes and memos between computers via a modem and phone line.

F-stop : F-stops indicate how open or closed the aperture on a camera lens is. The smaller the f number (for example, f2.8), the more light enters the camera.

Image Editor : A graphics program for altering bit-mapped images. The difference between image editors and paint programs is not always clear-cut, but in general image editors are best used for modifying bit-mapped images, such as scanned photographs, whereas paint programs are better for creating images.

Inkjet printer : A type of printer that works by spraying ink on a sheet of paper. Inkjet printers are capable of producing high quality print approaching that produced by laser printers. A typical inkjet provides a resolution of 600 dpi.

Image filter : A function that changes the appearance of an image. Filters are used to increase brightness and contrast, as well as add textures, tones and special effects to a picture.

ISO : Referring to the International Standards Organisation, the ISO number indicates the sensitivity of different camera films to light The slower the 'speed' of the film (e.g. ISO 100), the less sensitive it is to light.

Layer : In computer graphics, a layer is one of several onscreen 'drawing hoards' for creating elements within a picture. Layers can be manipulated by the designer, and the sum of all the layers makes up the total image.

PC Cards : A credit card-sized device, such as a modem, designed for use on notebook and handheld computers.

PDA : Stands for Personal Digital Assistant, a generic term for any small, electronic personal organiser.

Pixel : Short for picture element, a pixel is a single point in a graphic image. For example, monitors display images by dividing the screen into thousands - or millions - of pixels, arranged in rows and columns.

Removable storage : Disk drives that use high-capacity disks which can be removed Typical examples include lomega's Jaz and the Syjet from SyQuest.

Resolution : Refers to the sharpness of an image. The term is most often used to describe monitors, printers and bitmapped images. In the case of dot-matrix and laser printers, the resolution is measured by the number of dots per inch. For example, a 300 dpi printer is one that is capable of printing 300 distinct dots in a line one-inch long. This means it can print 90,000 dots per square inch. For graphics monitors the resolution signifies the number of dots - pixels - on the entire screen. For example, a 15in VGA monitor shows 640 x 480 dots, or about 50 dots per inch.

Retouching : Making subtle changes to an image in order to remove flaws or add new elements

SCSI : Stands for Small Computer Systems Interface. A standard high-speed parallel interface used to connect PCs to peripheral devices such as disk drives and scanners.

True Colour : Refers to any graphics device or software that uses at least 24 bits to represent each dot or pixel. Using 24 bits means that more than 16 million unique colours can be represented. Since humans can only distinguish a few million colours, this is more than enough to accurately represent any colour image.

VGA : Short for Video Graphics Array. Often taken to refer to its resolution, 640 x 480.

File Formats

BMP : The standard bitmapped graphics format used in the Windows environment. By convention, graphics files in the BMP format end with a .BMP extension. BMP files aren't very efficient and tend to be large.

GIF : Short for Graphics Interchange Format. This is mainly used for web graphics

JPEG : Short for Joint Photographic Experts Group, and pronounced jay-peg. This compressed format can reduce bitmapped images to about 5 per cent of their normal size,but this is achieved by losing some image detail.

PCX : Originally developed for ZSOFT's PC Paintbrush program, PCX is a bitmap graphics file format for PC graphics programs. Files in the PCX format end with a .PCX extension. PCX files tend to be large.

PNG : Short for Personal Network Graphics. This is a development of the old Graphics Interchange Format or GIF. Mainly used for web graphics.

PhotoCD : A file format for storing digital photographs developed by Kodak. Approximately 100 images can be stored on one disc. PhotoCDs are multi-session recordable CDs, which means that you can add images at a later date.

TIFF : Stands for Tagged Image File Format, one of the most widely used file formats for storing bitmapped images on both PCs and Macintoshs. Files in TIFF format often end with a .TIF extension. These are commonly used in faxing and can be compressed.

Format Suitable For: Sample File Size
Format Web Email Printing Photo printing Kilobytes*
GIF(256 colour) Yes Yes Yes No 7,250
JPEG (standard) Yes Yes Yes Yes 2,038
PNG No No Yes Yes 18,471
TIF (LZW) No No Yes Yes 25,371
BMP No No Yes Yes 25,366
PCX No No Yes Yes 31,082
*File Sizes of an A4 photo scanned at 300dpi, in 24 colour and then Saved in PaintShop Pro 5.0





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