GDI
Abbreviation for Graphics Device Interface

GIF
Abbreviation for Graphics Interchange Format: popular file format for LZW compressed raster graphics data, developed by CompuServe. More information about it can be found on this page.

gimbal mount
Mount whose axes of rotation are orthogonal and fixed in space.

global correction
A color correction technique that is applied to an entire image area. While global correction makes the same correction everywhere in the image, local color correction is only applied to a given area of the image that is localized through a mask.

glyph
A character shape or a graphic symbol that provides the appearance or form for a character. A glyph is the visual representation of a character. A font is actually a collection of glyphs. The word is derived from the Greek word for “carving”.

GOE
Pantone GOE is a color specification system for the graphic arts industry. It consists of 2058 colors that all are identified using a unique name. When you buy the GOE kit from Pantone, you get software as well as the GoeGuide, a thick bundle of strips that show all of these colors. GOE is based on 10 Pantone mixing bases, plus Pantone Clear. This makes it cheaper for printers to create those 2058 colors on demand.

goniometer
Measurement device to analyze light that is reflected at different angles. This is particularly important for glossy and pearlescent surfaces.

gothic
Refers to sans serif typefaces - see blackletter

GPIB
Abbreviation for General Purpose Interface Bus, an industry-standard interface used to connect peripherals devices, such as color scanners, to desktop computers. Nowadays completely replaced by SCSI and FireWire.

GRACoL
Abbreviaton for General Requirements for Applications in Commercial offset Lithography, general guidelines and recommendations that can be used as a reference source across the US print industry for quality color printing.

gradient
See blend

granularity
A measure of the non-uniformity seen in a large, evenly exposed image. This granularity pattern is caused by the microstructure of processed silver halide emulsions and is generally seen on continuous tone images. Smaller numbers mean less grainy images

gravure
A highly cost-effective printing method, ideally suited to high-volume printing with relatively inexpensive paper. A gravure press uses plate cylinders that have millions of small cells. These will fill with ink that is subsequently transferred to the printing paper. The cells are carved into the plate using lasers or diamond styluses. By varying the depth of these cells, great control over the range of ink tones can be achieved. Gravure presses can be huge, ideally suited to print runs that have millions of impressions. The paper used in the gravure process needs to be relatively soft and have an extremely smooth surface. Contrary to offset printing in which a rubber blanket can conform to paper irregularities, gravure presses have unyielding plates that come into direct contact with the paper. Any irregularities in the paper surface, when used on a gravure press, will miss contact with the cells carrying the ink. The tiny dots that create gravure printing can create excellent images, but without the depth and final image quality of offset printing.

gray balance
Combinations of cyan, magenta and yellow colorants that appear similar to shades of gray. It is important to maintain the neutrality of the gray throughout the proofing and printing process.

gray level
With image input and processing, a given amount or value related to an original image as seen through a color separation filter. Older scanners only stored 64 gray levels; today it is common to stare 256 gray levels. Although 256 levels are considered more than sufficient to render smooth transitions, some systems offer up to 1,024 gray levels.

gray levels
With image output, the number of differentiation’s that can be recorded on film or paper. The number of gray levels possible depends upon the output resolutions and the halftone screen ruling.

gray scale
- A narrow strip of paper containing an orderly progression in definite steps or patches of gray densities or printing halftone steps ranging in dot size from 0 to 100%. A gray scale is used to analyze and optimize the contrastive black and white and colored reproductions.
- A strip of light to dark gray tones placed at the side of original copy when photographed to measure tonal range contrast.

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