- Gamma:
1) A measure of contrast in photographic images. 2) In electronic color correction, the difference in the status of the color curves. The color curve represents highlight to shadow values between current values and corrected values. Changing the color curve (making a gamma correction) increases or decreases the highlights, midtones and shadows relative to the original points on the curve.
- Ganged / Ganging:
The grouping of two or more versions on a press sheet for greater efficiency.
- Gate Fold:
An insert where one or two pages are bound into a publication so that one or more pages will fold out from the publication.
- GIF:
An 8-bit computer file format by Compuserve. Capable of only supporting 256 colors or shades of grey at the most, GIF files are almost never used for professional printing.
- Gigabyte:
An electronic unit of measurement equal to about 1,000 megabytes of data (or 1,000,000 bytes). Abbreviated GB.
- Gloss:
A shiny coating on paper. Gloss coatings allow very little ink absorption, thus providing excellent color definition and contrast.
- Gradation:
Variation in tonal values, from white to black.
- Grain:
1) In paper making, the direction in which most wood pulp fibers lie within the sheet due to the direction of flow as the paper is made. Folding paper against the grain breaks more wood pulp fibers than folding with the grain, resulting in an uneven, less precise fold. 2) In film photography, the speckled appearance in prints or transparencies produced by clusters of silver particles in photographic emulsions. Frequently considered undesirable and apparent when an original is enlarged too much, grain can also be emphasized for special softening effects.
- Graphic:
A non-text item, illustration, photograph or artwork.
- Gray Component Replacement (GCR):
GCR is one of two basic methods (the other is UCR: Under Color Removal) in which “black generation” is achieved, and thus determines how black is added to the mix of the other process colors (cyan, magenta and yellow) when performing color separations. GCR separations actually replace with black, in varying degrees, the amount of CMY that is not only used to make neutrals in the image, but also other colors that are much less than neutral. The degree to which black replaces the other three process inks is determined by how much black is introduced into the color separation method; a high amount of black is referred to as “heavy black generation” or ”heavy GCR” while a very reserved use of black is referred to as “light black generation” or “light GCR, ” and what exists between these two strategies is referred to “medium black generation” or “medium GCR.” The color separation strategy of “maximum black generation” (maximum GCR) utilizes black to replace all or almost all of the other three process colors, and should only be used in special situations where the image content would benefit from it being dominated by black ink while minimizing, if not negating the use of cyan, magenta and yellow. There are two major benefits of utilizing GCR, especially medium and heavy GCR: 1) ink savings due the usage of less CMY ink by replacing these inks with K; 2) a higher degree of stability in holding color on press due to the fact that in using less CMY there is less of a chance for color to shift during a press run, yet achieving the same color appearance had black not replaced CMY.
- Grayscale:
A black and white image with shades of gray, such as a halftone.
- Gripper Edge:
The leading edge of a sheet which is held by the grippers.
- Gripper Margin:
The unprintable area of the paper where it is gripped as it passes through the press.
- Gutter:
The inside margin from the printing edge to the binding area for publications.