Glossary of Terms

CAD

Stands for Computer-Aided Design. Generally vector-based software that is used in the printing industry for packaging structural design, but it can also drive laser forme cutters for cutting and creasing dies, or cutting tables for signage (though normally the cutting layout is incorporated as a separate layer within a graphics file).

Capping

Covering the printheads when the printer is not in use for an extended period. This helps to prevent solvent ink evaporating and drying in the heads, or in the case of UV inks, it protects them from stray UV light. Normally capping is performed automatically by the printer, either as part of the "sleep" process after a set time of disuse, or on shut-down.

CMYK

The abbreviation for the primary transparent ink colours needed to an acceptably full range of colours for something like a photograph. Stands for Cyan, Magenta, Yellow and Black. The letter K is used for black, partly because it avoids possible confusion with B for Blue. K actually stands for Key, dating back to when colours were printed in four separate passes (as is still often the case for screen printing). Black was printed first, then this image was used as a guide, or key, to register (align) all the other colours to. See: RGB, colour separation, process colour. See Spot Colour, Process Colour.

Colour

A sensation produced by different wavelengths of light falling on the retina of the eye. The eye perceives visible light in effect as mixtures of three components, red, green and blue. Equal mixes produce white, and no light produces black.

Colour gamut

The complete range of colours that can be printed possible from a particular combination of printer, inks and medium. Offset printing inks are quite limited when using CMYK colours only, but many screen process and inkjet ink sets have significantly wider CMYK gamuts. Some printers also offer orange, red, green or violet process colours to extend the gamut further.

Colour management system

A means of achieving standard colours from a variety of different devices by referring their results to a known colour space model.

Colour Management.

In current practise this usually means processing the colours in software using small files called profiles that compensate for the particular characteristics of the printer, ink and medium being used.

Colour Matching System

A way of defining and standardising colour for reproduction through printing and other visual technologies. Commercial systems such as Pantone supply reference books of colour patches, with instructions on how to match these colours by mixing standard colours of inks.

Colour separation

The result of splitting a coloured original image into its component parts for printing. A full-coloured photograph will normally be split into cyan, magenta, yellow and black separations, and these will be carried on individual films (for screen process), printing plates and cylinders (for lithography, flexography, gravure etc)or output channels (for inkjets and other digital printers).

Colour space

A description of the total range of colours achievable by a particular process. This includes the colours discernible by the average human eye; those for a bee or a dog would be quite different.

Computer-to-Screen (CtS)

A range of methods and technologies have been developed to print a screen process stencil directly onto the screen mesh, instead of using emulsion coated stencils exposed through a piece of film. The processes include inkjet (either a water-based ink or a wax phase-change ink), digital light process (essentially a digital projector system) or laser exposure.

Continuous Inkjet (CIJ)

A continuous Inkjet generates a stream of ink droplets all the time, with the stream directed towards or away from the media by deflectors of various types (typically electrical fields or air jets). Some early signage and photography inkjets such as Iris or Du Pont Digital Cromalin used continuous inkjets, but these have all been replaced by Drop On Demand Types. CIJ is mainly used today by Kodak in its Versamark and Prosper series of high speed commercial web inkjets. See: Drop On Demand.

Contone

Short for continuous tone. It originally applied to silver halide photographs, where intermediate tones can be infinitely variable between white and solid. Film is an analogue process. Some computer printers such as inkjets and dye sublimation devices can simulate contone, even though they use digital input information.

Corel Draw

A vector drawing program. The main competitor to Adobe Illustrator. It's seen as cheaper to buy and is supplied with a healthy set of fonts, clip art and other items (though the price differential has become less obvious since Adobe adopted its Creative Cloud rental policy). However, pre-press operators tend to prefer the EPS and PDF output from Illustrator. See: Adobe Illustrator, EPS, PDF

Creasing

The process of pressing or scoring a crease line into media, usually paper or card, so that it can easily be folded later. This is normally done after printing, for carton packaging, greetings cards and similar work that needs to be folded at a later stage of production, or perhaps supplied flat to the customer for later folding.

Cutting

A range of processes variously to reduce printable substrates to manageable sizes for handling, then to fit them to the size needed for the printing process, and then to trim them to the final size dictated by the job itself.