Applications

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.

Super-calendering

See Calendering

TIFF

(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).

Variable Information Printing

See Variable Data Printing

Vector Graphics

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.