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Glossary of Printing Terminology

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Gamut
The range of different colours that can be interpreted by a colour model or a specific device.

GCR (Grey Component Replacement)
The act of replacing neutral greys in an image that have been produced using a mix of process colours (cyan, magenta, yellow) with a black tint only. This reduces the amount of ink being applied to the paper in these areas while on the presses.

Ghent PDF Workgroup
An international assembly of industry associations that establishes graphic arts workflow specifications, most notably PDF/X.

Ghosting
There are two types of ghosting:
a) An image that appears as a lighter area on a subsequent print, due to local blanket depressions from previous image areas.
b) Spoiling of a print by an image on it of work on the reverse side that has interfered with its drying, so that differences in the trapping of some colours or variations in gloss are apparent.

GIF Graphics Interchange Format
An image file format with built in compression, commonly used in web pages. Because of its 256-colour limitation and having been designed for on-screen use only GIF is not suitable for photography or press output.

Gloss
Gloss can refer to the reflectivity of paper itself or to the printed result on it. Gloss of paper is measured by using a Gardner Gloss meter, which measures reflected light at an angle of 75 degrees, and is expressed in Gardner Gloss units – the higher the number, the glossier the paper surface.

Glyph
A character within a font, but not necessarily from the standard alphabetic set. A glyph can be a dingbat or a typographic variant built into the font.

GRACol
General Requirements and Applications for Commercial Offset Lithography. US based standard for process control. It is about to be aligned with ISO 12647.

Graduated Screen
A ‘screen’ is a series of ink ‘dots’, printed on to a paper, which gives the appearance of a solid colour. The depth of screen colour can be deepened by increasing the dot frequency (see dpi) or the converse. A graduated screen is one where the dpi is varied across the screen so that you get a fading/deepening effect across the printing.

Grammage
Another expression of gsm or g/m squared, used to express the weight of paper or board (see g/m squared).

Graphic Design
The art of visual communication using text and graphics to promote a message. The design of logos, graphics & images to be used inbrochures, newsletters, posters, signs, TV, Web, and many other media types are all forms of graphic communication. Today's graphic designers often use desktop publishing, photo manipulation and illustration software and techniques to achieve their goals."

Graphic Papers
Papers for printing and writing.

Gravure Printing
Process in which recesses on a printing cylinder are filled with ink and the surplus removed by a blade. The paper contacts the cylinder and ‘lifts’ the ink from the recesses before depositing it on the paper. Generally used for long run printing, eg magazines and catalogues, because of the high cost of cylinders.

Greenhouse Effect
The natural greenhouse effect is necessary for all living species. An excessive greenhouse effect due to human activities is causing unwanted warming of the lower atmosphere. Certain gases in the atmosphere, such as water vapour and carbon dioxide, do not prevent short wave solar radiation from reaching the earth; but they hinder the escape of the longer wave reflective radiation from the atmosphere. The latter thus heats the atmosphere, resulting in a greenhouse effect.

Greyscale
An image composed of greys as opposed to colour or purely black and white. A typical 8- bit greyscale can.

Gripper
A device on a printing machine for holding the sheet during the printing or finishing process.

Gripper Allowance
The margin of paper along the gripper edge of the sheet, which is held by the grippers and which therefore cannot be printed.

Gripper Edge
The edge of the sheet presented to the gripper or on e edge of the plate that is fitted to the leading clamp of the cylinder.

GSA (Google Search Application)
This is an enterprise search application that allows companies to use Google for finding data.