Scanner Buying Guide
Film & Slide Features
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ADF (Automatic Document Feeder) - A scanner accessory that automatically feeds a stack of paper into the scanner.
Analog Signal - A signal in which information is relayed via waves of fluctuating voltage.
Anti-Aliasing - Because pixels are square, curved edges tend to appear blocky when viewed up-close. Anti-aliasing adds additional pixels around these edges that wash the color out and create the illusion of a smooth curve.
API (Application Program Interface) - A series of pre-built instruction sets provided by an operating system. A computer program will use these to accomplish a number of functions or tasks simply.
Bit (Binary digit) - Represents one unit of the basic binary code (0 or 1) with which the computer works. A number of bits together are used to represent a character in the computer.
Bandwidth - The amount of data that can be transmitted in a fixed amount of time. Some of the different measurement schemes include Hertz and Bits Per Second.
Batch Processing - Basically, the automated processing of a number of tasks. With scanners, this usually means scanning multiple documents automatically, with little or no user input.
Bit - A binary digit. The most basic representation of the binary code (0 or 1) with which the computer works.
Bit Depth - The number of individual colors or shades of a color that a device can process. This number is usually expressed in bits. Some of the more common bit depths are:
2-bits - 4 colors
8-bits - 256 colors
16-bits - 65536 colors
24-bits - 16,777,216 colors
Any bit depths higher than 24 stores control information in the additional space. Bitmap An image made up of individual pixels.
Bitonal - A scanner that outputs 1 bit per pixel, resulting in an image composed entirely of pixels that are either black or white.
Buffer - A temporary data storage area, usually in RAM, that helps keep frequently accessed data available without having to access the hard drive.
Byte - 8-bits. Basically, a unit of measurement that is capable of storing one character.
CCD (Charge Coupled Device) - A semiconductor memory device that works as an image sensor. These basically makes up the "eyes" of a scanning device or video camera.
Character Recognition - The ability of a device to recognize alphanumeric characters, like letters of the alphabet.
CIS (Contact Image Sensor) - An image sensor, similar to a CCD, used in some scanners. These are smaller than CCDs and use less energy, but are also less sensitive.
Color Depth - The number of individual colors that a device can process.
Compression - Shrinking the size of a file using a software algorithm. This smaller file is than able to be transmitted faster.
Controller - A device that transfers information between a computer and peripheral devices.
Device Drivers - Small programs that tell the computer how to communicate with a particular peripheral device.
Digital Signal - A signal that uses a stream of binary data (On and Off signals) to transmit the color intensity of a pixel.
Diffusion - The spreading of pixels in a bitmap image to give the illusion of more colors than are actually being used.
Dots - The small cells that visually combine to form images and characters on a page. When shown onscreen they are referred to as Pixels.
dpi (Dots Per Inch) - The amount of pixels that are able to be read in a single inch. More dpi means higher resolution and greater detail.
Duplex - A scanner capable of reading both the front and back sides of a page in a single pass.
Duty Cycle - How many times a device can reliably be used in a given period of time, usually a month.
Dynamic Range - See Optical Density.
Endorser - A scanner accessory that places an ID label on a document as it is processed.
Energy Star Compliant - A program of the E.P.A. and U.S. Department of Energy that endorses products that are energy efficient.
Enhanced Bit Depth - Expanding a scan's color depth through software.
Enhanced Color Depth - See Enhanced Bit Depth.
Film / Slide Scanners - A type of scanner that processes film slides, transparencies, and photo negatives. These scanners produce exceptionally detailed images by projecting a light through the media and scanning them with extremely sensitive sensors.
FireWire - An extremely fast external connection standard used with highspeed devices like hard drive and video cameras. FireWire supports simultaneous connections of up to 63 devices and transfer speeds up to 400 megabytes per second.
Flatbed - The most common type of scanner. These feature a flat glass plate, upon which the media is placed, and a moving sensor element that reads the media.
Grayscale - The shades of gray that a device can recognize, listed in bits. Grayscale usually ranges from 1-bit (only black and white) up to 8-bits (256 shades of gray).
Hardware Resolution - See Optical Resolution.
IEEE 1394 - See FireWire.
I.Link - See FireWire.
Imprinter - See Endorser.
Interface - A means of communicating between two different systems.
Interpolated Resolution - Enlarging a scan's resolution through software.
Interpolation - A software algorithm that enlarges the size, resolution, and/or color of an image. It is sometimes used to increase the bit-depth claims on scanners.
I/O Port (Input/Output Port) - A bi-directional port that allows data to be transmitted back and forth between devices.
ISIS - A popular software interface for high-speed scanners.
KB (Kilobyte) - 1,024 bytes. A unit used to describe smaller amounts of memory.
Landscape - When a page or image is oriented horizontally, so that it is wider than it is tall.
Light Source - Where light originates from in a device. With scanners it is the type of lamp used to illuminate the media being scanned.
Lynx - See FireWire.
MB (Megabyte) - 1,048,576 bytes. A basic measurement of computer memory.
Monochrome - The use of only one color, usually black.
MS (Millisecond) - One-thousandth of a second. A basic measurement of a device's access speed.
MTBF (Mean Time Between Failures) - The average amount of time that a component works before failure.
Negative - A piece of film that contains a reversed-tone image. This is the original film that prints are made off of.
OCR (Optical Character Recognition) - The ability of a scanner, with the proper software, to capture, recognize and translate printed alphanumeric characters into machine readable text.
Optical Density - A measure of the tonal range a scanner is able to detect. The range runs from 0.0 (white) up to 4.0 (black). The higher the optical density, the more accurate the range of tones in the final scan.
Optical Resolution - The actual amount of pixels a scanner can read. The higher the resolution, the better the final image.
Orientation - The relative direction of a display or printer page, either horizontal landscape or portrait orientation.
Pixel (Picture Element) - The small cells that visually combine to form images on a screen. When printed on a page they are referred to as Dots.
Plug-and-Play (PnP) - A configuration standard that allows a newly installed device to set itself up in an operating system automatically.
Port - The interface in which you hook-up components to a computer system. The common scanner ports are SCSI, USB FireWire, and Parallel Port.
Portrait - A page or image that is oriented vertically, so that it is taller than it is wide.
PPM (Pages Per Minute) - The standard unit of scanner speed. Basically, how many pages per minute a scanner can process.
RAM (Random Access Memory) - A temporary data storage found in computers and some of their components. It acts as a holding area for data that is waiting to be used.
Reliability - See MTBF.
Resolution - Density of pixels in a scanned image, measured in dots per inch (dpi). The higher the resolution, the greater amount of detail may be shown.
Sample Rate - See dpi.
Scanning Area - The actual surface area that a scanners sensor element is able to read from.
Scanning Element - The device in a scanner that actually reads the document. The two most common types of scanning elements are CIS and CCD.
SCSI (Small Computer System Interface) - An industry standard for connecting peripheral devices and their controllers to a PC. Different types of SCSI include:
SCSI-1 - These basic connections use an 8-bit bus, a 25-pin connector, and supports transfer rates up to 4 MB per second.
SCSI-2 - These drives use a 50-pin connector and support multiple devices. The transfer rate is the same as SCSI-1
Wide SCSI - As the name indicates, these drives feature a wider cable and a 68-pin connection that supports 16-bit data transfers.
Fast SCSI - While only using 8-bit bus, the Fast SCSI is able to transfer data at 10 MB Per second.
Fast Wide SCSI - These types of drives double both the bus (16-bit) and the data transfer rate (20 MB per second).
Ultra SCSI - Also known as Ultra Wide SCSI, it uses an 8-bit bus while transferring data at 20 MB per second.
SCSI-3 - These drives have a 16-bit bus and transfers data at 40 MB per second.
Ultra2 SCSI - Featuring an 8-bit bus and transfers data at a rate of 40 MB per second.
Wide Ultra2 SCSI - The latest standard, these use a 16-bit bus and support data transfer rates of 80 MB per second.
Sheet Fed - A type of scanner that automatically feeds one or more sheets of paper past a stationary scanning element.
Simplex - A scanner that reads one side of a page.
Slide - A frame of film that has been mounted in a plastic casing for use in a slide viewer or projector.
TWAIN - A popular software interface for average-speed scanners and digital cameras.
USB (Universal Serial Bus) - A Plug-and-Play external connection standard used to hook-up many different types of devices. It comes in two flavors:
USB 1.1 - Transfers data up to 1.5 MB per second and supports the simultaneous use of up to 127 devices.
USB 2.0 (Hi-speed USB) - Transfers data up to 60 MB per second and is backwards compatible with USB 1.1.
USB Hub - A device that adds additional USB ports to a computer.
VESA (Video Electronic Standards Association) - A group made up of industry professionals that sets standards for the manufacture and implementation of computer video devices.
Video Interface - A type of scanner connection that uses a vendor-proprietary interface card. It is used as an alternative to SCSI in some high-speed scanners.
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San Diego, CA 92123
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