Actual Size: One of the View menu commands. Displays the image at the image output size (the size the image would be if printed at the same resolution used for the scan). The actual size is equal to the size of the scan area as modified by the Reduce/Enlarge value. See also output size.
adaptive dithering: See convert.
Automatic Background Adjustment: A feature of the Apple scanner that allows more detail to be brought out from the dark areas of the original document by automatically adjusting the brightness level as the scanner scans dark areas of the document.
bilevel image: A one bit per pixel image containing black and white values but no grayscale information.
bit: A single binary digit consisting of either a zero or one.
bitmap: A set of bits that represents the graphic image of an original document in memory.
brightness: The parameter that determines the overall whiteness of the image during a halftone or grayscale scan. Increasing brightness results in a lighter overall image. Decreasing brightness results in a darker overall image.
buffer: An area in memory set aside for the specific purpose of holding data until it is needed. A “staging area.”
capacitor: An electronic component capable of holding an electrical charge.
carriage: The light-sensitive scanning mechanism, including the lamp, that moves along the scanner bed during a scan.
carrier: The mechanism, including the lamp, that moves along the scanner bed during a scan.
central processing unit (CPU): The “brain” of a computer or peripheral device; the microprocessor that performs the actual computations in machine language.
charge coupled device (CCD): A circuit board in the Apple Scanner that consists of a series of light-sensitive capacitors holding a positive charge. Thre are 2,592 active elements on the CCD (300 dpi x 8.5 inches maximum width).
character: Any symbol that has a widely understood meaning and thus can convey information. There are 256 possible characters, corresponding to the range of 8-bit binary numbers (0-255).
Chubbybits: One of the View menu commands. Displays an image using a square of four screen pixels for each dot in the image. Use the Chubbybits view for editing the image.
composition: Instructs the scanner whether to process a scan area as line Art, halftone, or grayscale. See also line art, halftone, and grayscale.
continuous tone art: Original documents that
contain ranges of grays or colors; for example, photographs.
contrast: The parameter that condenses or expands the range between black and white for halftone mode or grayscale mode. A high contrast setting records different shades of gray, emphasizing blacks and whites. A low contrast setting records different shades of gray, emphasizing middle gray shades at the expense of blacks and whites.
convert: A process performed by AppleScan that creates a line art or halftone document from a grayscale document. Available when you choose Convert from the File menu.
Converter Window: The window showing the current grayscale document ready for conversion. Use this window to set convert areas and specify whether they are to be line art or halftone.
CPU: see central processing unit.
daisy chain: A method of connecting peripheral devices so that as each device receives a signal from the host computer it has a chance to block the signal, getting the attention of the computer, which then communicates directly with the device. This method enables a number of devices to be connected to a single SCSI connector.
data: Any representation, such as characters or analog quantaties, to which meaning is assigned. In the Apple Scanner, image data consists of black and white (or gray) dots, representing dots on the original document.
density: See reflective density.
desktop publishing: A system that provides the ability to produce publication-quality documents. A Macintosh computer, an Apple LaserWriter printer, and page layout software provide this capability. Adding a scanner to the system extends the system’s capabilitiy.
detail panel: A panel revealed by zooming the Scanner window to show the scanner image at an expanded size. Used for creating scan areas precisely.
device: A hardware component of a computer system, such as a video monitor, disk drive, or laser printer.
digital halftoning: The process of digitally scanning a continuous tone image in halftone mode. This creates an artificial halftone pattern that simulates levels of gray by creating a dither pattern. See also dither pattern, halftone pattern.
digital image preprocessor (DIPP): A module in the Apple Scanner that converts analog information into computer-readable digital information. It also applies user/application program requests to the analog data.
direct memory access (DMA): A technique that allows a peripheral device to control data transfer in and out of the computer. DMA is efficient because it allows data to be transferred directly into and out of peripheral devices without having to go through the computer's CPU.
dither pattern: The matrix of threshold values used to represent gray shades in a black and white electronic image. See halftone pattern.
dot: A picture element (pixel) detected by the scanner. The size of a dot is determined by the scan resolution. At a resolution of 300 dots per inch, 300 dots are detected in each vertical and horizontal inch.
Dot for Dot: One of the View menu commands. Displays the image with one screen pixel for each dot in the image
dots per inch (dpi): see resolution.
entire image area: The rectangle that encompasses all the scan areas. If you use only one scan area, the entire image area is equal to the scan area. Two or more scan areas can be set in AppleScan; should there be a lot of extra space between them, the entire image area can be very large in comparison to the scan areas.
Fatbits: One of the View menu commands. Displays the image with a square of 16 pixels for each dot in the image. Use the Fatbits view for editing the image.
filter: A program or “mask” that alters data in accordance with specific criteria, formula, or algorithm.
firmware: Programs stored permanently in read-only memory (ROM).
flatbed: Type of scanner where the original document is placed on a glass like that of a photocopier and remains stationary, while the optical sensing mechanism moves under the original. This allows for precise positioning of the original and the ability to scan books and large documents.
gamma correction: see graymap setting.
graymap setting: A setting in AppleScan that establishes a relationship between the 16 levels of gray that the scanner detects and the actual range of gray shades between black and white in the original.
grayscale: A method of scanning in which the scanner assigns a binary number, representing a level of gray, to each scanned pixel. This allows for storage and display of true continuous tone images.
halftone: A composition mode that uses combinations of black and white dots to represent shades of gray. In the halftone process used in printing, the number, pattern, size, and shape of the dots can be varied. In electronic processing, only the number and pattern of the dots can be varied. The human eye perceives a close approximation between a good halftone representation and the original shades of gray. In AppleScan, halftone mode instructs AppleScan to record shades of gray using a pattern of black and white dots. Use halftone mode to scan photographs, drawings, and other originals so that the image shows shades of gray. See halftone pattern.
halftone pattern: The matrix of 16 threshold values that determine the patterns of black and white dots that represent different shades of gray in a Halftone mode scan area. You can change this pattern using any combination of 16 threshold values.
host computer: Any microcomputer equipped with an SCSI port, and capable of sending commands and parameters to the Apple Scanner and retrieving image data from the Apple Scanner.
image: The result, residing in memory, of scanning an original.
irregular scan area: A nonrectangular scan area created with the Irregular Scan Area tool. In effect, AppleScan uses a series of tiny rectangular scan areas to approximate curved or diagonal lines in an irregular scan area.
lamp: The special fluorescent light used by the scanner to illuminate the original during a scan. The light reflected from the original is detected by the scanner and recorded as electronic information.
line art: A composition mode that instructs the scanner to record each dot on the original as either a black or a white dot. Use line art mode to scan text and line drawings that contain no gray shades. If you scan an original that contains gray shades, the threshold parameter determines the level at which a gray shade is recorded as black or white.
line memory: A module in the Apple Scanner that reduces resolution from 300 dpi to the resolution specified by the user.
measuring units: The calibration of sizes displayed in AppleScan. You can display the size of objects in inches, centimeters, pixels, or picas. The measuring units affect the rulers in the Scanner window, the output size display in the Reduce/Enlarge dialog box, and the mouse location panels in the Tools menu.
orientation miniwindow: The special window added to the Fatbits view that displays a portion of the image so that you can see the context of the displayed image.
original: What you place on the scanner glass. The original can be a document, a photograph, or an object, such as a coin, that you want to scan.
output size: The size an image would be if printed at the same resolution used for the scan. The output size is equal to the size of the scan area as modified by the Reduce/Enlarge value.
parameter: A variable that is assigned a value and then provided in the parameter list of a function call or command when calling or invoking the call or command.
phototypesetter: A high-resolution—usually expensive—printing device primarily used by publishers. Some phototypesetters use laser printing technology and PostScript.
PICT: A file format for saving scanned documents. Scanned images saved in this format can be manipulated by most Macintosh programs.
picture element: A black or a white dot, a group of which make up a monochrome computer display. An individual dot recorded by a scanner.
pixel: See picture element.
pixmap: The area used by Color QuickDraw for drawing grayscale images.
Preview: An instruction to the scanner to make a preliminary scan of the entire scanner glass so that you can see which areas of the image you want to include in the final scan. Preview uses line art composition, the current Threshold and Graymap settings, and a resolution of 75 dots per inch. Preview ignores any other instructions you may have established.
QuickDraw: The set of optimized routines in the Macintosh ROM that are used to draw all objects on the screen. Color QuickDraw is used for drawing grayscale images.
RAM: See random-access memory.
random-access memory (RAM): Memory that can be both read and written into (changed) during the operation of a computer system.
read-only memory (ROM): Memory whose contents can be read but not changed. Information is placed into ROM only once, during manufacture. It then remains there permanently, even when the computer or device’s power is turned off.
Reduce to Fit: One of the View menu commands. Displays the image as small as necessary to fit within a standard Macintosh window. Use Reduce to Fit to see an entire image on screen.
Reduce/Enlarge: Controls for changing the scale of the image during a scan. Depending on the resolution value, you can make the image larger or smaller by a percentage of the size of the original, or you can establish the output size you want and AppleScan will automatically reduce or enlarge the image as necessary.
reflective density: A measure of the amount of light a dot reflects as it is scanned. Black dots reflect less light than white dots and gray dots reflect an intermediate amount.
resolution: (1) A measure of the ability to delineate visual detail, which is usually specified in dots-per-inch (dpi). The higher the value, the finer the detail of the image.
Resolution: (2) A parameter that determines how finely the scanner scans the original, expressed in dots per inch. The Resolution parameter determines the number of dots detected horizontally and vertically.
Scan: The instruction that begins the scanning process. Scan uses the composition you have set for each scan area, the current settings appropriate for each composition, and any Resolution and Reduce/Enlarge values you have entered. AppleScan displays the resulting image in a document window.
scan area: An area within the 8.5 x 14-inch scanner glass that indicates the size and location of the area to scan. You can define one or more scan areas for each scan.
scan image: The image resulting from scanning an original document.
scanner: Any graphic input device that converts printed matter into bit (digital) data.
scanner glass: The glass surface that makes up the top surface of the Apple Scanner. This glass surface is where the user places the original document to be scanned.
scanner image: The image displayed in the Scanner window.
Scanner window: The window that shows the scanner image. Use either panel of the Scanner window to set scan areas.
sheet-fed: Type of scanner where the original rolls past a stationary optical sensor. This means you cannot scan books or documents larger than the sheet-fed device.
ROM: see read-only memory.
sampling: The process of dividing an original document into equal-size sections (1/300th of an inch square) and transforming each section into a black, white, or gray dot.
scan area: An area drawn in the scanner window that indicates the size and location of the area to be scanned.
screen frequency: The number of lines (rows of dots) per inch. In traditional typesetting it refers to the screen that is used to produce halftones photographically. Generally, newspapers use a screen frequency of 65 to 85, and magazines use 133 to 150.
SCSI: Acronym for Small Computer System Interface, a standard developed to permit extremely high-speed data transfer among peripheral devices and a personal computer.
SCSI bus: The physical path on which electronic data travels between SCSI devices.
SCSI chain: A group of SCSI devices connected using the SCSI cable system. For example, a Macintosh Plus connected to an SCSI hard disk, a tape backup device, and a printer would be a SCSI chain.
SCSI connector: The specially configured end pieces of the SCSI cables that conect to the SCSI port on the back of the Macintosh and to each other.
SCSI device: Any device that can communicate on the SCSI bus, including your computer and any SCSI peripheral device.
SCSI ID number: A number set in a SCSI device that identifies it on the SCSI bus. The computer and other devices use this number to locate each device and distinguish it from the other devices in the SCSI chain. This number also determines which device communicates on the SCSI bus when more than one device wants to use the bus at the same time.
SCSI port: The input/output point on the SCSI bus for data (electrical signals). The port includes the connector on the back panel of an SCSI device and wiring inside the device. The SCSI port allows data to pass through the SCSI bus.
SCSI priority number: A setting that establishes rank among the devices on your SCSI chain of devices. On the Apple Scanner, the priority is set with the priority setting switch on the back of the scanner.
settings: Instructions that establish how the scanner will detect and record shades of gray. The settings include the Threshold, Contrast, Brightness, Halftone Pattern, and Graymap settings.
Show Page: One of the View menu commands. Displays the image as it would appear on an 8.5 x 14-inch page. In the case of images that extend over more than one page, Show Page shows as many pages as are necessary to print the image.
spool: A programming technique that allows access to more information that can be stored in memory at one time. By storing the majority of the image data on disk, you only need to have in memory as much as you want to display. The rest of the picture data can be read into memory (spooled) from the disk, and can replace the old displayed portion of the picture.
stepper motor: The stepper motor is a 24 volt DC motor that moves the scanner carrier arm assembly in precise increments under the original being scanned.
Threshold: The setting that determines the level at which a gray shade is recorded as either black or white. A high threshold setting results in a lighter overall image. A low threshold setting results in a darker overall image.
TIFF: Acronym for Tag Image File Format. A file format standard supported by some page layout and painting applications. Saving a scanned image in TIFF format alows the image to be imported into these applications.
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