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Specialty Graphic Imaging Association
SGIA Glossary

Definition Glossary

Sixth Edition

Language and our ideas about how it is interpreted change rapidly. The Specialty Graphic Imaging Association (SGIA) is aware of this and continues its effort to keep our constituents well informed about changes to the increasingly complex industry terminology. This publication represents the most recent changes.

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gable roof lock

A type of display lock used in gable roof construction.


A shallow metal tray used to hold type.

galley proof

A reader proof taken of type in a galley before it is formatted into pages.

gallon (gal)

A US unit of volume or capacity in the US Customary System used in liquid measure equal to 4 quarts or 3.785 liters.


Process of coating steel frames with rust resistant zinc.

galvano screen

Specialized rotary screen used for long runs on a rotary screen printing press.


(1) A measure of contrast in photographic images; (2) Mathematical curve representing both contrast and brightness of an image.

gamma correction

A non-linear tonal correction, editing an image gamma curve.

gamma curve

The shape of a line connecting the input and output values responsible for generating an image.


Greatest possible range.

gamut chart

A small text image for evaluating the reproducible colors in process color printing.

gamut color

The cleanest, most saturated color that can be reproduced by a set of process inks on a given substrate.

gamut compression

Editing an image to reduce the color gamut so that the image can be displayed or output within the limits of a particular device.

gamut mapping

Plotting the color of an image into the CIE color space.

ganging up (gang)

The reproduction of a number of different jobs or multiples of a single job that print as a single impression.

garment discharging

A process that allows the printing of dyed-dark textiles with light colored designs, by using sulfoxylate reducing agents with special dyes; refer to discharge printing.

gas chromatography

An analytical instrumental method of determining the composition of volatile solvents and oils.

gas crazing

Under certain drying conditions, the wrinkling of a printed film produced with tung oil.

gas mixer

A control valve for mixing air and gas.


Orifice through which liquid resin enters the mold in plastic molding processes.


An oversized page where both sides fold into the gutter in overlapping layers.

GATF star target

A quality control aid composed of a circular target approximately 17cm (5/8 in) with pie shaped wedges of lines that converge in the center (it is printed with color bars on the edge of a press sheet to detect dot gain, slur, and double images).


(1) Any of various instruments or tools for precise measuring; (2) to measure exactly; (3) a standard of measure, dimension, or capacity.

Gaussian blur

An image softening effect utilizing a bell shaped Gaussian distribution curve.


An European designation of a class of screen printing fabrics comprising both silk and synthetic fibers.


Acceptable acronym for gigabit.


(1) A state or condition where an ink or vehicle demonstrates a semi-solid or jelly-like consistency; can refer to deterioration to an unworkable condition; (2) partially cured plastisol ink that is dry to touch, 79°-116°C (175°-240°F) but not completely cured, 135°-171°C (275°-340°F).

gel point

The stage at which gelatin begins to form into a semi-solid consistency.


A glutinous protein type colloid used as coating for photographic film and screen emulsions.

gelatin emulsion type film

Any photosensitive film, or one that can be rendered photosensitive that is compounded to be water-soluable on a colloid base.

gelatin stencil

A screen printing stencil made from gelatin, colloid emulsion or film.

generation loss

The loss of quality that is unavoidable in any type of analog duplication, not present in digital duplication.


Any person or company that produces hazardous waste as defined by the US Environmental Protection Agency (EPA).


Not identified by a specific trademark or trade name.

generic fiber codes

Acceptable acronyms developed by the International Standards Organization for manufactured fiber.

geometric distortion

Image deformation in a uniform manner.