Glossary Of Terms

The SGIA Glossary of Terms serves as an excellent industry terminology resource. It is the language by which we all communicate, without it universal understanding would be impossible. Language and our ideas about how it is interpreted change rapidly. SGIA is aware of this and continues its effort to keep our constituents well informed about changes to the increasingly complex industry terminology. The definitions are for general reference only. Usage may vary between companies, individuals, or national and country customs. The information presented is as accurate as the authors and editors can ascertain and SGIA assumes no responsibility for the use of information presented herein.


  • Gable roof lock
    A type of display lock used in gable roof construction.
  • Galley
    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.
  • Galvanized
    Process of coating steel frames with rust resistant zinc.
  • Galvano screen
    Specialized rotary screen used for long runs on a rotary screen printing press.
  • Gamma
    (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.
  • Gamut
    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.
  • Gate
    Orifice through which liquid resin enters the mold in plastic molding processes.
  • Gatefold
    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).
  • Gauge
    (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.
  • Gauze
    An European designation of a class of screen printing fabrics comprising both silk and synthetic fibers.