Application software is
that which carries out a specific task on data. Applications
are differentiated from the software that makes up the
operating environment of the computer or that controls
a server or network operation. Typical applications
for the creation of documents of on demand printing
include Quark XPress, Adobe PageMaker, CorelDraw, Adobe
Photoshop and high-end word-processing packages such
as Microsoft Word.
Banding
Rendering of a graduate tint by some
systems can produce banding, as the increment of the
tint is increased or decreased. Unless intentional (see
Posterisation) the
result is always undesirable.
Bit-depth
Bit-depth describes the number
of bits assigned by the computer to each pixel displayed
on a monitor. Thus, a monitor with a bit-depth of 1
would only be able to display a monochrome image (each
pixel would be 'on' or 'off'). Professional DTP systems
use 24-bit monitors to display 'true colour'.
Bits
Bits are units of information
in binary form — data rendered as one or a zero,
or an 'on' or 'off' condition. Bit is a short form for
`binary digit'. Bits are aggregated into bytes and other
units of measurement.
Bleed
Bleed refers to printing that goes beyond the edge of the sheet after trimming.
Calendering
Calendering is the last stage
in the paper making process: it involves passing freshly
coated papers through a set of heated and highly polished
steel rollers within the papermaking machine. By varying
the pressure and number of rollers involved, different
finishes from matt to gloss are produced. Very high-gloss
finishes are produced by 'super-calendering'; repeating
the calendering process on another offline set of rollers.
Cased
Our term for a hardback book.
CMYK
(Cyan, Magenta, Yellow and Black) CMYK is the abbreviation for the four process
colours used in standard four-colour printing, and most
- but not all - colour digital printers. Cyan, magenta,
yellow and black are known as subtractive primaries.
These colours provide the widest colour gamut with the
smallest number of inks.
Coated Papers
Most papers used in magazines and brochures
are covered in a layer of coating, often made from china
clay or latex. Coatings are applied either by the papermaking
machine (Machine Coated) or offline (Process Coated).
The method by which this is applied, the materials and
adhesive used to bind it to the paper, affect the quality
of the final printing surface. However, coatings generally
provide a better printing surface, producing less dot
gain, better highlight definition and stronger colours.
Compression
Compression describes techniques
for reducing file sizes for storage or transmission
by applying an algorithm to the data. On receipt by
the receiving station a decompression algorithm reverses
the process. The objective of compression is to achieve
the reduction with the minimum of distortion to the
data, therefore 'lossless' compression is generally
preferred in graphic applications over 'lossy' compression
in which data is sampled selectively.
Contract proofing
A proofing standard which forms the
basis of the agreement between printer and publisher.
Traditionally, these have been produced from film or
plates (as wet proofs) but digital contract proofs are
gaining acceptance, despite the fact that many digital
systems are incapable of rendering halftone dots. Proofing
of on demand print jobs is often done on the press or
final output device.
Contrast
Differential between light and dark
areas of image.
CTP (Computer to Plate)
CTP or Computer-to-Plate describes a system in which the use of desktop publishing software, electronic prepress workstations, and platesetters allows the imaging of metal plates for any format of press without the use of film, stripping or traditional platemaking. This process results in lower costs while shortening the amount of time needed to get a job on the press.
DCS
(Desktop Colour Separation)
One of a number of commonly used image file formats,
with others including EPS
and TIFF. DCS
files contain five elements - a file for each of the
CMYK separations
and a preview image for layouts in PICT
format.
Digital Asset Management
Archiving and indexing of content for
reuse in print or alternative media is an increasingly
common trend as content owners recognise the long-term
value of copyright material.
Digital Offset
Digital offset printing systems
image the printing medium (usually foil or plates) on
the press. These systems have many of the productivity
advantages of purely digital systems, plus the ability
to produce longer runs at offset quality. They do not,
however, allow variable data printing, page picking
or electronic collation.
Digital Printing
Digital printing systems image
using data fed directly into the press, and do not require
intermediate media such as film or plates. The principle
benefit that this confers is the ability to vary the
contents of each page, and the overall structure of
the document. (See also Electronic
Collation and Page
Picking).
Direct to Press
A generic term to describe all printing
systems that take digital data into the press, embracing
both digital printing and digital offset machines.
Dithering
Dithering techniques are rather
like the impressionist painting technique of pointillism
— compensating for a restricted colour gamut by
simulating colours from adjacent dots of other colours
in a bitmapped image.
Dot gain
Dot gain describes the 'spread' of ink
outside the original circumference of each of the dots
making up the image. The condition is, to some extent,
predictable and can even be simulated in some proofing
processes. The variables include the type of stock,
the inks and the condition of the press. In effect,
dot gain produces a greater intensity of colour —
not always desirable — as a consequence of increased
ink density.
DPI (Dots Per Inch)
Output resolutions are expressed in
DPI which is a measurement of resolution of a printed image as determined by the number of dots that fit into one inch. The higher the concentration of dots per inch, the sharper the image will be.
Electronic
Collation
In the conventional printing model,
pages are printed and then collated into the finished
document. Digital printing enables the printer to predetermine
the page order within the document and then to print
the pages in that order.
GCR
(Grey Component Replacement) GCR is a technique for adding an element of black
to any area of a printed sheet with neutral tones, i.e.
those covered by all three of the other process colours.
The effect is to add contract and sharpness but over-compensation
results in murky shadows.
Gamma
The gamma coefficient expresses
the relationship between colour intensity on input and
output. An important concept within colour management,
the gamma values can be used to calibrate a monitor,
because it represents the difference between a colour
value on disk and that actually displayed. It is a measurement
of the compression or expansion of light and dark shades.
Gamut
The colour gamut of a system
defines the limits of the shades and hues, which can
be displayed or rendered on screen or in print.
Greyscale
Each pixel on a greyscale monitor can
display gradations from white to black. This is important
for reasonable quality display of halftone black and
white images.
Gutter
The gutter is the space between the printed area and binding, also known as the margin.
HiFi colour
HiFi colour is a term coined
by the American Davis Inc. consultancy but which has
gained more general usage to describe a range of technologies
which expand the traditional CMYK printing gamut (see
CMYK). Five, six
and even seven colour systems have been developed to
create dramatic or photo-realistic printed pieces. A
number of on demand printing systems offer an expanded
colour gamut by adding additional coloured toners and
inks.
Highlight
Highlights are those areas of
an image nearest to white: some scanning and image manipulation
programs require the operator to set the 'white' and
'black points' (not to be confused with the white point
of a monitor).
Imposition
Imposition is either a manual
or digital technique for arranging sets of separations
into the printing formes required by the printer. In
on demand environments, imposition is a digital process.
Interpolation
Interpolation is a technique
used in some compression and scanning applications to
enhance data by logical deduction. For example, some
low-resolution scanners use interpolation to
increase the optical resolution of the device by using
an algorithm to make assumptions about a missing pixel
from those surrounding.
Limp
Our term for a paperback book.
LPI
(Lines Per Inch)
Frequencies of halftone screens are expressed in LPI which is the number of dot lines created per inch, which provides an indication of image sharpness. For most commercial printing, screens vary from 55 (newspapers)
to 200 (brochures), but some applications where quality
is paramount demand screens of 300 LPI and above.
Margins
Margins are the unprinted area around the edges of a page.
Mask
Masks are used to isolate an
area of an image for manipulation. Mask can be
drawn on screen using a mouse or digitising tablet,
but are more often created by sampling colours within
the image to define the area. Those elements not selected
are unaffected by the manipulation or editing process.
Moiré
Interaction between separations or misalignment
creates an optical effect called moiré,
in which parts of the printed image seem to shimmer.
The effect can also appear when a pre-screened image
is re-screened for reproduction, for example, when scanning
a printed original. Many scanning applications have
a 'de-screen' option to overcome the problem.
Object-Orientated
Whereas bitmapped images are defined
by values attributed to pixels, object orientated graphics
are described by mathematical co-ordinates. Graphic
elements are described as a set of mathematical values
describing an outline and fills, and can be imported
into other packages and re-sized, without having to
revert to the package in which they were created.
Offset Lithography
Offset lithography is a printing process where the image prints by transferring ink from a plate to a rubber blanket that deposits the ink onto the substrate instead of directly from plate to paper. Also known as Offset Printing.
Page
Picking
A digital printing technique which allows
the printer to select pages, from a database, for inclusion
in an individual document. (See also Electronic
Collation).
PDF
(Portable Document Format) PDF is a document transfer format developed by
Adobe. The principle advantages of PDF for printing
are that the format is both platform independent and
encapsulates all of the elements of the document (including
embedded fonts) necessary for its production. The PDF
format is also being developed as the basis for future
production workflows as well as file exchange.
Perfect binding
Perfect binding is a binding method where all pages are trimmed to a single sheet. They are clamped together and a cover is wrapped around the spine. The pages are attached to the cover using and adhesive. We only offer perfect binding for digital premium books produced on our Xerox iGen3. Our standard binding method is slotted binding.
PICT
PICT is a Macintosh file format
for bitmapped or object-orientated graphics.
Plotter
A term inherited from the CAD world
to describe a large format inkjet printer.
Posterisation
A deliberate form of banding, in which
the increments between gradations are increased to show
the changes in shade.
PostScript
PostScript is the page description
language developed by Adobe as the common standard for
the printing and publishing industries.
PPI
(Pixels Per Inch)
Scanner resolutions are measured in PPI.
Prepurposing
The creation of content with more than
one medium in mind.
Reflectives
Photographic, printed or artwork originals
for scanning — those originals from which light
is reflected, i.e. those which are not transparencies.
Registration marks
The lines, dots and other marks on film
separations to allow them to be lined up. Sometimes
doubling as crop marks, registration marks also appear
on proofs to show the trim area of the page.
Repurposing
The reuse of content — usually
digital and frequently in media other than print.
RGB
(Red, Green, Blue)
Whereas most colour print images are made up from the
MCYK process colours, the picture on a colour display
— as with television — is built up from
combinations of red, green and blue. These are known
as the additive primaries.
RIP
(Raster Image Processor) RIPs are either software programs (running on
a powerful computer) or a dedicated piece of hardware
which carry out the rasterisation process - converting
a digital image into a pattern of dots for output on
film, plates or paper.
Rosette
With conventionally screened images,
i.e. non-stochastic, patterns of dots form into rosettes
when the separations are overlaid. Printers look for
clear rosette patterns and a sign of good registration.
Screen angles
To avoid moiré, each of the separations
in process colour printing have to be offset. The screen
angles determine the degree of offset.
Slotted binding
Slotted binding where small slots or notches are made in the binding edge of the sections and filled with adhesive to hold the pages together. This is our standard binding style which we believe produces a stronger book than perfect binding.
Soft proofing
Soft proofing is a technique
of previewing a page on screen. The difficulty has been
achieving accurate representations of colour with the
two technologies of printing and monitors using two
different colourspaces (see CMYK
and RGB). Professional
monitors are usually sold with calibration tools to
improve the colour match.
Stochastic screening
From the Greek 'to guess', stochastic
screening renders an image as an apparently random scattering
of much smaller dots than would be found in conventional
screening. Consequently, there are no rosettes, but
stochastic methods are capable of producing a high quality
image at relatively low resolutions.
(Tagged Image File Format)
Along with EPS, the
TIFF format is one of the most common formats
for image file exchange.
Trapping
No printing press is perfect, and to
allow for registration errors, which could show fine
white lines between adjacent colours, trapping
software creates a small overlap between colours.
UCR
(Under Colour Removal) UCR describes a method of replacing elements
of cyan, magenta and yellow with black to avoid an undesirable
build up of ink on the printed sheet in dark areas.
Variable Data Printing
Digital printing provides the ability
to vary text and image elements on the page, and also
the page composition of the document as a whole (see
Electronic Collation
and Page Picking).
The use of geometrical primitives such as points, lines, curves, and polygons, which are all based upon mathematical equations to represent images in computer graphics. It is used by contrast to the term raster graphics, which is the representation of images as a collection of pixels (dots).
Versioning
The technique used in digital printing
systems to create numerous versions of a basic document
— typically, different language versions.
