OBJECT-ORIENTED GRAPHICS: Images saved in vector file formats are stored as points, lines, and mathematical formulae that describe shapes making up an image. When vector files are viewed on your computer screen or printed, the formulae are converted into a dot or pixel pattern and displayed as a bitmapped image on the monitor. Since all of these pixels are not part of the file, the image can easily be re-sized without losing quality. Photographs are not usually saved in this type of format. Some computer users, especially Mac OS users, call this file type object-oriented and sometimes you see that term used within graphic drawing programs. Vector files have a similar technology to what Adobe Systems employs with its PostScript fonts and has all of the same advantages: you can make any font as big as you want while retaining its quality.

OCR: Optical Character Recognition. This is a technique used by scanning software to convert scanned text documents into a form that can be later edited using word processing software. In other words, OCR software optically recognizes scanned text as graphics and then converts it into words that can be edited as words that are using word processing programs, such as Microsoft Word.

OCTAL: Is the base eight in mathematics and harkens back to an ancient time when computers used 6-bit bytes that could easily be written using a two-digit octal number. (Arent you glad you know that?)

OFFICE: Microsofts ubiquitous suite of software applications that includes Word, Excel, PowerPoint, Internet Explorer, and depending on which variation and operating system you use, Outlook, Access, Publisher, and others.

OFF-LINE: Anything not under the direct control of the computers CPU (Central Processing Unit) is said to be off-line. The opposite is on-line for operations directly under control of the CPU.

ONE-OFF: A CD-ROM disc made one at a time instead of being stamped from a glass master disc the way CDs are made in volume. When a new CD-ROM disc is in production a test disc or one-off will be created for approval purposes. CD-ROM recorders are sometime called one-off machines because they write a single discone at a time.

ON-LINE: Anything under the direct control of the CPU is said to be on-line. The opposite is off-line for operations not directly under control of the CPU.

ON-LINE SERVICES: An on-line service is an electronic sourcea supermarket might be a better analogythat lets you research encyclopedias, the content of newspapers and magazines, as well as make and check airline reservations, send and receive e-mail and much, more. While on-line services, such as CompuServe, started as stand-alone services, they eventually migrated into value-added Internet Service Providers proving users access to the World Wide Web.

OPERATING SYSTEM: Often called simply OS, this is the master software that controls your computer. When you turn on any computer, the OS is the first thing that gets loaded into the computers memory. It interacts with your computers ROM (Read-Only Memory) or BIOS (Basic Input Output System) chips to accomplish tasks like controlling the hardware components of your system and how they interact with you through on-screen communications.

OPTICAL DRIVES: Optical removable media drives are more correctly called magneto-optical and use a laser to heat and change disc reflectivity to produce media that can be erased and reused. Writing data to optical media requires three spins: The first erases existing data, the second writes the data, and the third verifies the data is there. When compared to fast magnetic drives, all this spinning tends to reduce performance. Typical performance specifications for magneto optical drives (based on a typical Fujitsu 230MB unit) are seek times of 30ms, access time of 40ms and average write transfer rate of .44MB per second.

OPTICAL RESOLUTION: Scanners are measured by their optical as well and an interpolated resolution. Optical is the raw resolution of the scanner thats inherently produced by its hardware, while interpolated resolution is a software technique thats used to add pixels to simulate a higher resolution. How well your scanner does this depends on the software, but in general the average user will be pleased with the results. Purists, however, will ignore the scanners interpolated resolution specifications and base their purchasing decision on the optical resolution only.

OS: See Operating System

OS/2: A single user operating system developed by IBM that provides a graphical user interface (like Microsoft Windows and the Mac OS) as well as a command line structure. OS/2 is a multitasking operating system, which means users can have more than one program active at the same time. Trying to cash in on many computer users infatuation with Star Trek, IBM created OS/2 Warp, an enhanced version of the original operating system that includes multimedia support, and Internet capabilities. It didnt work.

ORANGE BOOK: The fourth step in the evolution of CD-ROM standards was called the Orange Book and defined specifications for recordable CD-ROM discs. Part I of the Orange Book was written for CD-MO (Compact Discs-Magneto-Optical) discs, where data can be written, erased, and rewritten. Part II defines standards for CD-WO (Compact Disc-Write Once) where data cannot be erased. Youll sometimes hear these drives called WORM for Write Once Read Many times.

OTI: Open Tool Interface

OUTPUT: The analog form of information produced or generated by a computer. While historically this means data printed on some form of device, it now means any kind of real world translation of data, including photographs, overhead transparencies, slides, or even negatives. Output can be in many different forms: An image can simply be viewed and cataloged on a monitor. Photographs can be transferred to other computers in digital form by floppy disk or any kind or removable media and viewed on another computer. A printer attached to your computer can produce a gray scale or color page. If in the past the selection of photo-realistic printers was limited and expensiveall thats changed. Now you can use the growing number of high quality and inexpensive color printers from Canon, Epson, HP, and Lexmark to print images directly from your computer.