| glossary |    |
| glossary | |
24-bit color
24-bit color images are composed of three 8-bit color channels. Each color channel,
similar to an 8-bit grayscale image, contains up to 256 colors. When combined,
the red, green and blue channels provide up to 16.7 million colors. 24-bit color
is also known as True Color and Photo-realistic Color.
36-bit color
36-bit color images have 3 color channels of 12 bits each - one channel each
for red, green and blue, When combined, the red, green and blue channels provide
up to more than 1 billion colors.
8-bit grayscale
Images that contain 256 possible shades of gray.
Address
A number that identifies the I/O location of the device to the host computer.
Alpha channel
An 8-bit channel reserved by some image-processing applications for masking
or additional color information.
Analog
Continuously variable signals or data. Description of the continuous wave or
signal (such as the human voice) using an electrical voltage variation. Used
for voice, visual, and computer data communication. The digital or pulse output
of a computer or terminal must be converted to an analog signal before it can
be transmitted over analog grade lines
Anti-aliasing
The rendering of hard-edged objects so they blend smoothly into the background.
A technique for merging object-oriented art into bitmaps.
Application Software
General term referring to software packages. For scanner-related application
software, they usually function as editing, drawing and optical character recognition
(OCR).
ASCII (American Standard Code for Information Interchange)
Standard by which many computers assign code numbers to letters, numbers and
symbols. Used for text exchange between computer platforms.
Aspect Ratio
The ratio of horizontal and vertical units
Automatic Configuration
An MiraScan driver feature that automatically finds the available I/O address
to use
Automatic Exposure
An MiraScan driver feature that automatically sets the suitable brightness and
contrast for the user.
Automatic Preview
An MiraScan driver feature that automatically present a preview instantly whenever
brought up.
Banding
A visible stair-stepping of shades in a gradient.
Bit
A unit that can hold information on or off with values of 1 and 0, respectively
Bit depth
The number or bits used to represent each pixel in an image, determining its
color or tonal range
Bitmap
An image formed by rectangular grid of picture elements (pixels). The computer
assigns a value to each pixel, from one bit of information (indicating black
or white) to 24 bits per pixel (for full-color computer displays), to as many
as 64 bits per pixel for some types of full-color images. A bitmap is an image
defined by a collection of dots, as opposed to a vector image, which is defined
by mathematical formulas.
Brightness
A measurement of image intensity
Byte
An unit that contains 8 bits representing values 0 to 255.
Calibration
A process that extracts some runtime dynamic information from devices
CCD
A charge-coupled device, or CCD, is a light sensitive electronic device that
converts light into an electrical charge.
CMYK (Cyan, Magenta, Yellow, Black)
The subtractive primaries, or process colors, used in color printing. Black
(K) is usually added to enhance color and to print a true black.
Color channel
Color images on the computer are created by combining different color channels.
In RGB, the most commonly used color model, the channels are red, green and
blue.
Color Match
Match the color between source device and destination device.
Color separation
The division of an image into its component colors for printing. Each color
separation is a piece of negative or positive film.
Compression
Encoding the bits of information in an image file so that it takes up less space
when stored. Compression results in little or no distortion.
Continuous-tone
Image with complete range of tones from black to white such as photographs,
paintings and drawings. Negatives or positives with a broad range of tones that
have no screened dots.
Contrast
The relativity between the light and dark areas of an image. The more the difference,
the greater the contrast.
Data compression
"Squeezing" of data for the purpose of transmission through put or
storage efficiency. Portions of the data are removed by an algorithm that will
restore the data when needed.
DCS
Desktop color separation is an image format consisting of four separate CMYK
PostScript files at full-resolution, together with a fifth EPS master for placement
in documents.
Decompression
The expansion of compressed image files. See also lossy and non-lossy.
Default
Command or parameter that takes effect if no other option is specified.
Density
The ability of a material to absorb light. Measurement of the light transmission
of a transparent or translucent object or the light-absorbency of a reflective
surface. In photography, measurement of the opacity of a transparent or translucent
object. On a film negative, the greater the density area, the more black or
more developed it is. Density is measured from 0 to 4.0. It is calculated by
measuring the reflectance or transmittance of light and calculating theoretical
light absorption.
Descreen
Removal of dot patterns during or after scanning printed matter by defocusing
the image. This avoids moire patterning and color shifts during subsequent reprinting.
The Descreen filter is used for the image printed out by dithering. Without
the Descreen filter process, the scanned dithering image will have a moire effect.
Dialog Box
A window that allows user to make options, key in data and receive messages
Dither
A technique that uses dispersed dots to simulate gray shades to fool the eye
into seeing grayscale data
Dot
Smallest visible point that can be displayed on a surface.
DPI
An acronym for dot per inch. A measurement of resolution.
Driver
A program functioning as a bridge between application software and hardware.
It usually encapsulates the hardware details to provide easier interface with
the application software.
Drum scanner
An optical input device that mounts reflective or transparent input media on
a revolving cylinder for digitizing.
EPS (Encapsulated PostScript)
This format carries a pict preview and is the only format that supports saving
line screen data and transfer functions. In bitmapped mode, it also supports
transparent whites.
Export
To output data in a form that another program can read.
File
A named collection of information stored as an apparent unit on a secondary
storage medium such as a disk drive.
Film
Photosensitive material, generally on a transparent base, which will receive
character images, and may be chemically processed to expose those images. In
image setting, any photosensitive material, transparent or not, may be called
film.
Film negative
A piece of film with a reversed image, in which dark areas appear white, and
vice versa.
Flatbed scanner
Any scanning device that incorporates a flat transparent plate, on which original
images are placed for scanning. The scanning process is linear rather than rotational.
Gamma
A mathematical function used to describe the relationship between input densities
(levels) and output densities (levels.) The measurement of how compressed or
expanded dark or light shades become in an image.
Gamma Correction
An operation used to correct data that is not realistically reproduced by some
devices. In order to make the correction, the characteristic of the output device
(i.e., gamma value) must be known.
Gradation
A smooth transition between black and white, one color and another, or colorful
and colorless.
Gray balance
The balance between CMYK colorants required to produce neutral grays without
a color cast.
Gray levels
Discrete tonal steps in a continuous tone image, inherent to digital data. Most
CT images will contain 256 gray levels per color.
Grayscale
A range of intensity (i.e., gray shade) for a color plane.
Highlight
The brightest intensity for an image
Histogram
A graphic representation of the number of pixels with given color values,
showing the breakdown or distribution of color values in a picture.
Hue
The wavelength of light of a color in its purest state (without the addition
of white or black).
Image Type
The image type used to represent a document. It affects how information
is saved and therefore affects how original documents can be reproduced.
Input
Raw data, text, graphics, imagery or commands inserted into a computer.
Interpolation
The process of increasing the resolution of an image by the addition of
new pixels throughout the image, the colors of which are based on neighboring
pixels.
Interface Cable
A cable connecting the scanner with a host computer. In a PC system, it
connects to the PC through the connector on the SCSI interface card.
Interface Card
An I/O (input/output) card inserted into the host computer expansion slot.
It serves as a bridge between scanner and host computer.
Interpolation
An operation performed by the driver. It enhances the resolution of scanned
images by applying an appropriate algorithm to generate a new and higher resolution
image from a lower resolution image.
Inverse Image
A MiraScan driver feature that negates the grayscale value of each pixel
in an image.
JPEG (Joint Photographic Expert Group)
An image compression/decompression standard that divides the image area
into cells to condense information based on content analysis.
Line Art
A graph or image containing only lines, text and drawings
Lossless
Data compression algorithms that store data in a more efficient format and
won't cause any data loss in the compression process. Typically this type of
compression has a ratio of up to 8:1.
Lossy
Data compression algorithms that assumes some of the data in an image file
is unnecessary and can be eliminated without affecting the perceived image quality.
Typically this type of compression has ratios between 10:1 and 100:1.
LPI (Lines Per Inch)
A term used in printing as a measurement of the frequency of lines of a
screen (usually ranging from 55-200). LPI refers to the frequency of the horizontal
and vertical lines.
Luminosity
A value corresponding to the brightness of color.
LAW
The Lempel-Ziv-Welch image compression technique.
Mirror Image
A MiraScan driver feature that flips an image left and right
Moir?Pattern
An interference pattern usually unexpected and annoying
Monitor calibration
The process of optimizing the color settings of a monitor to match selected
colors of a printed output.
Monochrome
Single-colored. An image or medium displaying only black-and-white or grayscale
information, Grayscale information displayed in one color is also monochrome.
Neutral gray
Any level of optical density (from white to black) having no apparent hue.
It consists of equal levels of red, green, and blue (RGB).
Noise
In the scanning context, this refers to random, incorrectly read pixel values,
normally due to electrical interference or device instability.
Non-lossy
Image compression without loss of quality.
Non-Uniform Resolution
A MiraScan driver feature that allows horizontal and vertical resolution
to be different
Non-Uniform Scaling
A MiraScan driver feature that allows horizontal and vertical scaling to
be different.
Optical resolution
In the scanning context, this refers to the number of truly separate readings
taken from an original within a given distance, as opposed to the subsequent
increase in resolution (but not detail) created by software interpolation.
Original
A term used for any artwork or photograph that is scanned.
Output
Process of sending computer results to a CRT or printer.
PICT / PICT2
A common format for defining bitmapped or object-oriented images on the
Macintosh. The more recent format (PICT2) supports 24-bit color.
Pixel
The smallest picture element unit in an image
PostScript
The standard device-independent language developed by Adobe Systems that
describes the appearance of pages in documents. PostScript is a page in its
final form, ready for imaging on an output device. Encapsulated PostScript describes
a graphic, image or complete page in a final form that can be exchanged between
application programs. Under such circumstances one PostScript described item
can be included in another layout.
PPI (Pixels Per Inch)
A measurement of the amount of scanned information. The finer the optics
of the scanner the higher the scan resolution. PPI is equivalent to DPI.
Preview
An operation that gets a rough image of a document for setting parameters
and image analysis.
Preview Size
The size of the preview window area.
RAM (Random Access Memory)
The memory a computer needs to store the information it is processing at
any given moment. This is short-term memory and is lost when the power is shut
off. RAM may be expanded by adding memory chips or memory boards.
RGB (Red, Green and Blue)
The color model in which color images are composed of red, green and blue
color channels. Most computer displays and image editing programs use the RGB
color model.
Resolution
The measure of image details. The smallest discernible detail in visual
rendering. Resolution may be stated in terms of spot diameter, line width, pixel
matrix dimension, raster lines or dots/inch.
Sampling
The process of converting analog data into digital data by taking a series
of samples or readings at equal time intervals.
Saturation
The amount of gray in a color. The higher the gray content, the lower the
saturation.
Scaling
An operation that enlarges or shrinks an image
SCSI
An acronym for Small Computer System Interface. It provides an interface
to the computer system with device independence within a class of devices.
SCSI ID
A number for a device on the SCSI bus chain can be 0 through 7. This number
represents the device when it is communicating on the SCSI bus.
Shadow
The darkest intensity of an image
Sharpen
Electronic photo-retouching function for enhancing image detail and contrast
either globally or in selected regions of the picture.
Sheetfed
Type of scanning device in which the original is moved past the scanning
head, rather than having the scanner head moved. Usually appropriate only for
sheets of paper.
Single-bit images
Black and white bitmapped images, of either line art image type.
TGA (Targa)
A file format for exchanging 24-bit color files on PCs.
Threshold
A value for text data type. For pixel value above the threshold value, it
is represented by 1 (i.e., white). For pixel value below the threshold value,
it is represented by 0 (i.e., black).
TIFF (Tag Image File Format)
A popular image file format. It contains several effective compression schemes
which save space when storing data .
Tone curves
Also known as gamma curves. These are used to smoothly adjust the overall
tonal range of an image, or the individual tonal ranges of each color channel.
TWAIN
A standard software protocol and API (Application Programming Interface)
for communication between application software and image acquisition devices.
TWAIN-Compliant
A term that identifies application software or devices that follow the TWAIN
standard.
Zoom
A MiraScan driver feature allowing the user to see more details of the document.
Users can zoom-in on the scan area repeatedly.