Images that contain 256 possible shades of gray.
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.
32-bit color images have 4 color channels of 8 bits each - one channel
each for red, green and blue, plus 8 bits of grayscale data to provide
A device used to convert analog data to digital data. Analog data is
continuously variable, while digital data contains discrete steps.
Red, green, and blue light that, together, produce white light. These
are the primary colors of light from which all other colors can be made.
Compare with subtractive primaries.
Visibly jagged steps along angled lines or object edges, due to sharp tonal contrasts between pixels.
An 8-bit channel reserved by some image-processing applications
for masking or additional color information.
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.
Unequal scale change in the horizontal and vertical direction of a scanner.
This enables the scanner to adjust the ratio in the horizontal and vertical
The rendering of hard-edged objects so they blend smoothly into the background.
A technique for merging object-oriented art into bitmaps.
An ordered collection of elements of the same type. Represented by single
line of sensors in a CCD chip are called a linear array. A digital image
is stored as a 2-dimensional data array containing pixels addressable
by x,y (or row, column) coordinates.
A visible indication (defect) in an image, caused by limitations in the
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.
A visible stair-stepping of shades in a gradient.
Sequential scanning of multiple originals using previously-defined, unique
settings for each.
In object-oriented programs, a curve whose shape is defined by anchor
points set along its arc.
A type of image containing only black and white pixels.
Binary, or base 2, is a numbering system with only two digits, 0 and 1.
Binary is convenient for use with bits which have only two states, on
The smallest unit of memory in the computer. A bit can be either off or
on, representing a value of 0 or 1. Bits can be used in combination to
represent higher numbers.
The number or bits used to represent each pixel in an image, determining
its color or tonal range
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.
black & white
Refers to both line art and halftone bitmapped image types.
A movable reference point that defines the darkest area in an image, causing
all other areas to be adjusted accordingly.
The intensity of a color or tone regardless of its hue or saturation.
A unit of measure equal to eight bits of digital information.
The standard unit measure of file size. See also megabyte,
kilobyte, and gigabyte.
Setting equipment to a standard measure to produce reliable results.
On a negative, proof or printed piece, a strip of tones used to check
Copy assembled and suitable for photographing by a process camera with
minimum number of steps.
Any artwork or type that is ready to be prepared for printing.
A charge-coupled device, or CCD, is a light sensitive electronic device
that converts light into an electrical charge.
CCD (Charge Coupled Device)
A diode that is light-sensitive when charged with electrical voltage.
An off-press color proofing system developed by DuPont. The proofs are
single laminated sheets produced from film separations.
CIE (Commission Internationale de l'Eclairage)
An international group that has developed a set of color definition standards
endorsed by Adobe for PostScript Level 2.
clipping (sense 1)
Process of setting graphics display boundaries. The clipping volume is
defined by the window, near and far clipping planes, and projectors of
the corners of the window. Data on the planes forming the edges are considered
to be within the volume. (2) The conversion of all tones lighter than
a specified gray level to white, or darker than a specified gray level
to black, causing loss of detail. This also applies to individual channels
in a color image.
Color management system. This ensures color uniformity across input and
output devices so that final printed results match originals. The characteristics
or profiles of devices are normally established by reference to standard
1T8 color targets.
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.
An overall color imbalance in an image, as if viewed through a colored
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.
The process of adjusting an image to compensate for scanner deficiencies
or for the characteristics of the output device.
A utility for specifying colors on the monitor.
A representation of what the final printed composition will look like.
The resolution and quality of different types of color proofs can vary
Output or electronic files that contain image information for only one
The division of an image into its component colors for printing. Each
color separation is a piece of negative or positive film.
Three-dimensional model (or representation of a 30 model) used to organize
colors to show progressions of hue, lightness, and saturation. Device-independent
color spaces are based on international standards (CIE).
A photographic image on transparent film used as artwork. 35mm, 4"x5"
and 8"x 1O" formats are commonly used.
A light-sensitive device for measuring colors by filtering their red,
green and blue components, as in the human eye. See also spectrophoto-meter.
Comprehensive artwork used to present the general color and layout of
a page. See proof.
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.
The reduction in size of an image file. See also lossy and non-lossy.
Image that has a complete range of tones from black to white: photographs,
paintings and drawings. Negative or positive with a broad range of tones
that have no screened dots.
An abbreviation for continuous tone. A color or grayscale image format
capable of illustrating continuously varying tonal ranges, as opposed
to line art. CT is also the name of a file format used for exchanging
high-level scan information.
The relationship between the light and dark areas of an image. The more
extreme the difference, the greater the contrast.
Lines printed showing the dimensions of the final printed page. These
marks are used for final trimming.
"Squeezing" of data for the purpose of transmission throughput
or storage efficiency. Portions of the data are removed using an algorithm
that will restore the data when needed.
Desktop color separation. An image format consisting of four separate
CMYK PostScript files at full-resolution, together with a fifth EPS master
for placement in documents.
The expansion of compressed image files. See also lossy and non-lossy.
Command or parameter that takes effect if no other option is specified.
A measuring instrument that registers the density of transparent or reflective
materials. It is used to check the accuracy, quality, and consistency
of output. Colors are read as tonal information. See also colorimeter
The ability of a material to absorb light. Measure 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.
Removal of halftone dot patterns during or after scanning printed matter
by defocusing the image. This avoids moire patterning and color shifts
during subsequent halftone reprinting.
A special type of interference filter, which reflects a specific part
of the spectrum, whilst transmitting the rest. Used in scanners to split
a beam of light into RGB components.
Method of data storage and/or transmission wherein each element of information
is given a unique combination of numerical values (bits). Each bit indicates
either the presence or absence of a condition (such as on-off, yes-no,
true-false, open-closed). Digital data or voltages consists of discrete
steps or levels, as opposed to continuously variable analog data.
Digital-to-Analog Conversion (D/A)
Conversion of digital information into a state of fluctuating voltage
levels. (DAC) Interface to convert digital data (represented in discrete,
discontinuous form) into analog data (represented in continuous form).
direct-digital color proof
A proof made from a stored data file onto a substrate without producing
intermediate separation film.
Direct exposure of image data onto printing plates, without the intermediate
use of film.
Elimination of intermediate film and printing plates by the direct transfer
of image data to printing cylinders in the press.
Temporary visual representation of computer output on a CRT or other electronic
The process of specifying color to adjacent pixels in order simulate a
third color in a bitmapped image. This technique is used when a full range
of colors is not available.
The highest level of density of a film positive or negative.
The point of minimum density in an image or original.
Smallest visible point that can be displayed on a display surface.
A printing defect in which dots print larger than intended, causing darker
colors or tones. Dot gain measures the increase in halftone dot values
that occur during the offset printing production process. Total dot gain
is measured as the difference in apparent dot size between the final printed
product and the original film. Dot gain occurs as the result of both mechanical
and optical influences on the original dot size.
Minute, symmetrical individual subdivisions of the printing surface formed
by a half-tone screen.
The reduction in resolution of an image, necessitating a loss in detail.
A method of denoting the resolution of a scanned image, a digitized image
in a file, or an image as rendered by an output device. Also, used interchangeably
with pixels per inch (PPI).
An optical input device that mounts reflective or transparent input media
on a revolving cylinder for digitizing.
A printing process using small heating elements to evaporate pigments
from a carrier film, depositing these smoothly onto a substrate.
A type of halftone screen dot with an elliptical rather than circular
shape, which sometimes produces better tonal gradations.
The coating of light-sensitive material on a piece of film.
This specifies a readable film image with the emulsion side facing away
from the viewer. The printer usually decides whether emulsion should be
up or down.
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.
Another term used for DCS.
To output data in a form that another program can read.
A named collection of information stored as an apparent unit on a secondary
storage medium such as a disk drive.
Photosensitive material, generally on a transparent base, which will receive
character images, and may be chemically processed to expose those images.
In imagesetting, any photosensitive material, transparent or not, may
be called film.
A piece of film with a reversed image, in which dark areas appear white,
and vice versa.
Used in reference to color transparency recording devices, and sometimes
also to imagesetters.
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.
The use of cyan, magenta, yellow, and black in printing to produce a wide
variety of colors.
FPO (For Position Only)
A low resolution image placed in a document to indicate where the final
version is to be positioned.
A combination of hardware and software, designed to capture individual
frames from video clips for further digital manipulation, or consecutive
replay on computer platforms.
A mathematical function used to describe the relationship between input
densities (levels) and output densities (levels.) The measure of how compressed
or expanded dark or light shades become in an image.
The correction of tonal ranges in an image, normally by the adjustment
of tone curves.
The limited range of colors provided by a specific input device, output
device, or pigment set.
Sequential scanning of multiple originals using the same previously-defined
exposure setting for each.
GCR (Gray Component Replacement)
A technique for reducing the amount of cyan, magenta and yellow in an
area and replacing them with an appropriate level of black.
A unit of measure of stored data corresponding to one billion bytes of
1,024 megabytes, or 1,048,576 kilobytes of digital data.
A smooth transition between black and white, one color and another, or
color and the lack of it.
A relationship of the distribution of tone values in the reproduction
to the original.
The balance between CMY colorants required to produce neutral grays without
a color cast.
Discrete tonal steps in a continuous tone image, inherent to digital data.
Most CT images will contain 256 gray levels per color.
(1) An image type consisting of shades of gray, with no color. The standard
grayscale image contains 8 bits per pixel, which allows for 256 shades.
(2) The depiction of gray tones between black and white. A grayscale monitor
is able to display distinct gray pixels as well as black and white ones,
but not color pixels. (3) An orderly variable progression in definite
steps of gray densities ranging from minimum zero (white) to maximum density
(black). A strip of standard gray tones placed at the side of the original
copy during a photography to measure tonal range obtained. Used in processing
film or materials such as photographic paper and plates.
An simulation of continuous tones by the use of black or overlapping process
color dots of varying size or position.
A pattern of dots of different sizes used to simulate a continuous tone
photograph, either in color or black and white.
See quality factor.
A light line around object edges in an image, produced by the USM (sharpening)
A dot in a halftone screen that has smooth, crisp edges.
Reproduction technique in photography with high gamma in which the difference
in darkness (density) between neighboring areas is greater than in the
A very light original image (possibly overexposed) that contains important
detail in the highlight area.
The lightest or whitest part of an image with discernible detail. A highlight
is represented in a halftone image by the smallest dot patterns. A specular
highlight is whiter and lighter, but has no detail.
A graphic representation of the number of pixels with given color values,
Showing the breakdown or distribution of color values in a picture.
A color model based on three co-ordinates: hue, lightness (or luminance)
A color model based on three co-ordinates: hue, saturation and value.
The wavelength of light of a color in its purest state (without the addition
of white or black).
An output device used to render high resolution images or documents on
photographic paper or film.
Raw data, text, graphics, imagery or commands inserted into a computer.
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
JPEG (Joint Photographic Expert Group)
An image compression/decompression standard that divides the image area
into cells to condense information based on content analysis.
(1) Abbreviation for the color black. K is used so that it is not confused
with an abbreviation for the color blue. (2) Represents "kilobytes"
of information which is 1024 bits. The K is upper-case to distinguish
it from lower-case k, which is a Standard International Unit for "kilo",
The number of pixels sampled as a unit during image manipulation and sharpening
(K, KB) A unit of measure of digital information corresponding to 1024
bytes. Abbreviated and referred to as K.
1,024 bytes of digital data.
A shape or object printed by eliminating (knocking out) all background
colors. Contrast to overprinting.
Local Area Network. A group of connected computers in a relatively small area that share access to printers and other peripheral devices.
Computer output device that uses a laser to generate the character images. It uses some of the same methods to produce the final image as a copier.
Images containing only black and white pixels. Also known as bilevel images. The term line art is sometimes used to describe drawings containing flat colors without tonal variation, that is, a single-bit image type that lacks any dithering effect.
Data compression algorithms that store data in a more efficient format
that does not cause any data loss in the compression process. Typically
this type of compression has a ratio of up to 8:1.
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.
A dark image (possibly underexposed) that contains important detail in the shadow area.
Lines Per Inch. A measure of the frequency of a halftone screen (usually ranging from 55-200). Originally, halftones were made by placing an etched glass plate over an image and exposing it to produce dots. Lpi refers to the density of the horizontal and vertical lines.
A value corresponding to the brightness of color.
Look-Up Table. The table of colors a computer can display at a given time. The computer uses the table to approximate the desired color from the range it has available.
The Lempel-Ziv-Welch image compression technique.
A common format on the Macintosh computer for storing and transferring
low-resolution, monochromatic bit-mapped images. It originated with the
paint application of the same name.
The inactive area of a bitmapped image which will not respond to changes.
This often refers to a 2-dimensional array of CCD elements.
1,024 kilobytes or 1,048,576 bytes of digital data.
A device into which data can be entered, in which if can be held, and
from which is can be retrieved at a later time. Data is stored in digitally
encoded bits, and manipulated as needed during calculation processes.
The amount of memory a computer has directly affects its ability to perform
Tonal values located between highlights and shadows. Midtone definition controls the contrast in image reproduction by determining the separation of tones in the image.
Undesirable screen pattern in color process printing caused by incorrect
screen angles of halftones.
Electronic display unit that uses cathode ray tube to generate text, graphics
and imagery. It looks like a normal TV set, however, the monitor has a
much higher degree of resolution.
The process of optimizing the color settings of a monitor to match selected
colors of a printed output.
Single-colored. An image or medium displaying only black-and-white or
grayscale information, Grayscale information displayed in one color is
A texture similar to orange peel sometimes caused by sharpening. It is
particularly visible in flat areas such as sky or skin.
See film negative.
Any level of optical density (from white to black) having no apparent
hue. It consists of equal levels of red, green, and blue (RGB).
In the scanning context, this refers to random, incorrectly read pixel
values, normally due to electrical interference or device instability.
Image compression without loss of quality.
A type of drawing that defines an image mathematically rather than as
pixels in a bitmap.
OCR (Optical Character Recognition)
The analysis of scanned data to recognize characters so that these can
be converted into editable text.
A color proof generated prior to the production press run and prior to,
or in lieu of, a press proof.
A high-volume, ink-based printing process, in which ink adhering to image
areas of a lithographic plate is transferred (offset) to a blanket cylinder
before being applied to paper or other substrate.
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.
A term used for any artwork or photograph that is scanned.
Process of sending computer results to a CRT or printer.
Printing over areas already printed. Contrast to knockout.
A common format for defining bitmapped or object-oriented images on the
Macintosh. The more recent format (PICT2) supports 24-bit color.
Particles that absorb and reflect light and appear colored to our eyes.
The substance that gives ink its color.
Another term for picture element; the smallest raster display element,
represented as a point with a specified color or intensity level. A two-dimensional
array of dots that define the form and color of an image. Measurement
is indicated as PPI. (pixels per inch) The term pixel is usually interchangeable
with dot, but pixel most often refers to screen dots rather than image
dots. The eye merges differently colored pixels into continuous tones.
A means of reducing image resolution by simply deleting pixels throughout
PMS (Pantone Matching System)
A commonly used system for identifying specific ink colors.
PMT (Photomultiplier Tube)
A light sensitive tube that can detect very low light levels by amplifying
the signals applied to it. Usually associated with drum scanners.
The conversion of continuous tone data into a series of visible tonal
steps or bands. Intentional, as opposed to banding.
The standard device-independent language developed by Adobe Systems that
describes the appearance of pages in documents. PostScript describes 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
in a way that can be exchanged between application programs so that one
PostScript described item can be included in another layout.
PPI (Pixels Per Inch)
A measure of the amount of scanned information. The finer the optics of
the scanner the higher the scan resolution. PPI is equivalent to DPI.
Refers to the steps required to go from original to film.
Proof made before the final press run by exposing the film negatives or
positives to pigmented or dyed light sensitive materials. When assembled,
it will be similar in appearance to the finished printed product.
A preliminary or preview scan of an original to determine the correct
setup and cropping prior to full scanning.
A base color that is used to compose other colors,
Surface, usually made of metal, that has been treated to carry an image.
The plate is inked and the ink is transferred to the paper or other surfaces
by a printing press. Printing plates are also made of rubber, synthetic
rubber, and plastics.
The four colors (cyan, magenta, yellow and black) that are combined to
print a wide range of colors. When blended, these reproduce only a small
portion of all the colors found in nature, but they can reproduce the
widest range with the fewest inks when printing. See also CMYK.
The color characteristics of an input or output device, used by a CMS
to ensure color fidelity.
Working copy of some material used for review and approval. A reasonably
accurate sample of how a finished piece is intended to look.
A multiplication factor (between 1 and 2) applied to output screen ruling
to calculate scanning resolution for optimum output quality. This is also
known as the halftoning factor.
Tones between shadow and midtones are known as 314 tones and those between
highlight and midtones are known as 1/4 tones.
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.
A proof consisting of many images ganged on one substrate and positioned
with no regard to final page imposition.
A synonym for grid. Sometimes used to refer to the grid of addressable
positions in an output device.
An image composed of a pattern of dots or pixels. Same as a bitmapped
The process of converting mathematical and digital information into a
series of dots by an imagesetter for the production of negative or positive
film. See also RIP.
Artwork prepared so that it may be photographed or input into a computer
The alignment of different films or printing plates to produce one printed
Small cross-hairs on film used in the alignment of negatives.
Recorder element. The minimum distance between two recorded points (spots)
in an imagesetter.
Unit of measure of resolution in number of lines per millimeter, such
as RES8 or RESlOD. To convert RES to DPI, multiply the RES value by the
number of millimeters in an inch, 25.4 (For example, RES12 = 300 DPI).
An increase or reduction in the number of pixels in an image, required
to change its resolution without altering its size. See also down-sampling
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.
Art of making digital, chemical, or dye corrections by adding or removing
density or color, on continuous tone film, on color transparency materials
or on reflection prints. Digital retouching makes changes to pixel values
to enhance image appearance.
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 ROB color model.
RIP (Raster Image Processor)
Part of an output device that rasterizes, or converts mathematical and
digital information into a series of dots, so that it can be rendered
and imaged onto a screen, film, paper or other media.
The dot pattern created when all four color halftone screens are placed
at the traditional angles.
RPI (Rels per Inch)
A measurement of the number of discrete steps that exposure units in imagesetting
devices can make per inch.
The process of converting analog data into digital data by taking a
series of samples or readings at equal time intervals.
The amount of gray in a color. The higher the gray content, the lower
To change the proportion of an image by increasing or decreasing its
To examine or capture an image by means of a moving light beam. Scanning
technology is used in imaging, optical character recognition, and other
A device used to digitize images to be manipulated, output, or stored
on a computer.
To break up continuous-tone copy into dots for reproduction as a halftone.
Line screens are designated by the number of ruled lines they contain:
from 50 lines per inch to 500 lines per inch. The greater the number
of lines per inch, the sharper and fine the printed half-tone. The selection
of the screen is dictated by the paper, press, the nature of the copy.
The angles used to offset the different films in process color separations.
Proper screen angles are critical to minimize moire' patterns.
screen ruling or frequency
The number of lines per inch in the halftone screen. The lower the number,
the larger and more widely spaced the dots. Higher screen rulings allow
reproduction of fine detail.
SCSI (Small Computer System Interface)
An internal communications standard for computers, through which hard
drives, scanners, and other peripherals transfer data.
High-quality, contone reproduction of an image, intended to be identical
to the original.
Color obtained by mixing two primary colors, Although known as primary
colorants, C, M and Y are the secondary colors of light. Red plus green
produce yellow for example.
A business that specializes in outputting computer files on laser imagesetters,
film recorders, large-format plotters and other types of output devices.
The darkest part of an image with discernible details, represented in
halftone images by the largest dot patterns.
Electronic photo-retouching function for enhancing image detail and
contrast either globally or in selected regions of the picture.
Type of scanning device in which the original is moved past the scanning
head, rather than having the scanner head move. Usually appropriate
only for sheets of paper.
Black and white bitmapped images, of either line art or halftone image
A type of dot in a halftone screen whose edge is not smoothly circular.
This can create a fuzzier image. By contrast, a hard dot has a very
Isolated light pixels in predominantly dark image areas, sometimes caused
by incorrect readings or noise in the scanning device.
An extremely accurate color measurement device using a diffraction grating
to split light into its component wavelengths, which are then measured
by numerous light sensors.
Small reflection or detail highlight in a photograph that is reproduced
in halftone form with a 0% dot value.
Smallest region of an input or output image whose tone can be controlled
independently of all other regions. A digitally generated halftone dot
is constructed using a matrix of spots.
The preparation and assembling of film prior to platemaking.
The base material used to carry or support an image, for example paper
The inks (cyan, magenta, and yellow) used in printing to create different
colors. In contrast to additive primaries, these produce darker colors
when combined. Another term for primary colorants.
The capture of more gray levels per color than is required for image
manipulation or output. This additional data allows shadow details to
he heightened, for example.
A file format for exchanging 24-bit color files on PCs.
thermal wax transfer
A printing process using small heating elements to melt dots of wax
pigment on a carrier film, which are then transferred to paper or transparent
film by contact. This differs from the dye sublimation process in that
individual dots do not fuse together, so thermal wax transfer appears
to be of a lower resolution.
The point at which an action begins or changes. The threshold setting
used in scanning line art determines which pixels are converted to black
and which will become white. The threshold defined in the USM process
determines how large a tonal contrast must be before sharpening will
be applied to it.
The process of rendering all areas darker than a certain value as black,
and all lighter areas as white. Used to convert grayscale images to
black and white.
TIFF (Tagged Image File Format)
A file format developed by Aldus Corporation for exchanging bitmapped,
monochrome, and full-color images between applications.
A reduction in the range of the hues and values in an original.
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
A positive photograph on transparent film such as Agfachrome, Kodachrome,
or Ektachrome film, usable as copy for color separation and viewed by
transmitted light. A positive color image of the original drawing, painting
or scene on a colored photographic film is also referred to as a chrome.
An optical input system for digitizing images from small format positive
or negative transparency film.
A prepress technique which allows for variation in registration during
the press run. On the desktop, this is done primarily by allowing an
overlap between abutting colors.
An industry standard for software that controls optical input devices
such as scanners, film recorders and video capture interface cards.
Application programs that support TWAIN allow optical input devices
to be controlled from inside the application.
UCR (Undercolor Removal)
A technique for reducing the amount of magenta, yellow and cyan in neutral
areas and replacing them with an appropriate amount of black.
USM (Unsharp Masking)
The term comes from a conventional color separation camera technique
that uses a unsharp photographic mask to increase contrast between light
and dark areas of the reproduction and gives the illusion of sharpness.
A movable reference point that defines the lightest area in an image,
causing all other areas to be adjusted accordingly.
There are no terms beginning with 'V', 'X', 'Y' or 'Z' in this glossary.