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A B C D E F [G] H I J K L M N O P Q R S T U V W X Y Z

G

Gain.
  1. Camera adjustment which controls the strength of the camera's video signal, altering contrast and brightness of the picture.
  2. A projection screen's reflectivity. The higher the gain number, the brighter the picture, because more light is reflected back toward the projector (but less light is reflected to the sides). Gain (Audio) Increase the level of a sound by increasing the amplitude of the frequency.
Gain (Projection Screen).
The amount by which a reflective screen (or surface of some sort) reflects light.
Gamma.
Relationship between the original scene as filmed and input into a video display to the image actually produced on the video display.
Gamma Correction.
Adjusts the video display image to correspond with that seen by the video camera or video input when the gamma is non-linear. Gate Audio device that permits audio to pass through or mutes it electronically, depending on some criteria such as how loud the sound is.
Generation.
The number of duplication steps between an original recording and a given copy. A second generation duplicate is a copy of the original master and a third generation duplicate is a copy of a copy of the original master, etc.
Generation Loss.
When an analog master videotape is duplicated, the second-generation copy is usually inferior in some way to the master. This degradation appears as loss of detail, improper colours, sync loss, etc. Limited frequency response of audio/video magnetic tape and imperfections in electronic circuitry are the main causes of generation loss. Higher performance formats (such as 1-inch) exhibit much less generation loss than more basic formats. Digital formats make generation loss negligible because each copy is essentially an exact duplicate of the original. Video enhancing equipment can minimize generation loss. Some video processors pre-enhance the video signal to overcome generation loss.
Geometry.
Symmetrical nature of a video display creating vertical lines that run parallel up and down without bending or angling and creating horizontal lines that run side to side without bending or angling
Genlock
A method of synchronization involving the generation of a video signal sync-locked with another signal. Because they are synchronized, a genlocked signal can be mixed with the original signal, allowing dissolves, wipes and other transition effects. Genlock and frame synchronization differ in that genlock is the generation of a new signal synchronized to a video signal that is already present while frame synchronization takes two already-generated signals and synchronizes them. Genlocking two VCRs requires the use of a time base corrector (TBC).
Ghosting.
A weak, secondary, ghost-like duplicate video image in a video signal caused by the undesired mixing of the primary signal and a delayed version of the same signal.
Ghost Eliminator.
Electrical device to remove double images (ghosts) from a TV picture.
GIF.
Graphics Interchange Format, a popular bitmap format for storing image files with palettes of 2 to 256 colours. There are variations for animation sequences and for text.
GIF89a specification introduced transparency and animation.
Uses “Lempel-Ziv-Welch” (LZW) compression algorithm.
Typically used for 8-bit data.
Good for scenes containing few colours, hard edges (eg. diagrams); poor for full colour scenes.

GIF: Graphic Interchange Format uses a maximum of 256 colors, and uses combinations of these to create colors beyond that number. The GIF format is best for displaying images that have been designed using a graphics program, like logos, icons, and buttons.

GIF images come in two different versions and have some extra functionality that JPEGs do not. You can save GIF images in GIF 87 or GIF 89a format. GIF 89a is newer and has the following features that GIF 87 and JPEG files do not:

Interlacing:
if you save a GIF 89a image as interlaced, the browser will be able to display the image as it loads, getting gradually crisper and clearer until it is finished. Interlaced GIFs have slightly larger file sizes than non-interlaced GIFs, so you will have to decide whether the interlacing effect is worth the extra download time for your images.

Transparency:
with GIF 89a format images you can set a single color to be transparent, that is, it will allow the background color or image to show through it. Transparency is most commonly used to make the rectangular background canvas of an image invisible; this feature can be very effective in Web page design.

Animated GIFs:
GIF 89a images can also be animated using special software. Animated GIF images are simply a number of GIF images saved into a single file and looped. Netscape Navigator and Microsoft Internet Explorer can both display animated GIFs, but many other browsers cannot, and may not be able to display even the first image in the loop. Use animated GIFs with caution.

Gigabyte (Gb).
Storage measurement equal to 1,024Mb, or 1,073,741,824 Kb.
Gigahertz (GHz).
One billion Hertz (Hz) or one billion cycles per second.
Gradient background.
A background that goes smoothly from light to dark, or one colour to another, typically used behind titles.
Graduated filter.
Lens filter that's part clear and part coloured or dark, making perhaps 1/2 of the picture dark.
Graphic equalizer.
  1. Electronic audio device that cuts or boosts particular sound frequencies passing through it.
  2. A device type that applies a series of bandpass filters to a sound, each of which works on a certain range of the spectrum. The frequencies that fall within the range, typically one-third octave, can be boosted or cut.
Graphics accelerator card.
Graphic card that performs high speed rendering and video manipulations, relieving your slower standard graphics card of these duties.
Graphics card.
Computer circuit that holds the data for images sent to the screen and determines the resolution of the display.
Graphics projector.
Device designed to project images from graphics workstations displaying 12801024 images.
Graphics tablet.
Flat surface connected to an electronic pen or sliding puck similar to a mouse, connected to a computer allowing you to "draw" images electronically.
Group delay.
A phenomenon involving timing differences between video signal components. For example, a long cable run may introduce a substantial delay between the transmission of the colour and brightness video information resulting in shadows.
Graphic Equalizer.
Form of equalizer (device used to adjust or change a signal's frequency response typically by changing its amplitude) using multiple previously set, fixed frequency bands to adjust the amplitude of the waveform at those specific frequencies.
Graphics Grade Projector.
Cathode ray tube video projector with a maximum horizontal scan rate of 63,000 Hz making it capable of displaying line quadrupled video and S-VGA graphics at resolutions of 1,024 by 1,280.
Grayscale
Displays a palette based on 256 levels of gray—from black to white.
0 = black
255 = white
GPI trigger.
General Purpose Interface, a standardized input to a device (often a switcher) that causes the device to execute a preplanned maneuver when a signal from another device (often an editor) tells it to.
Grille.
Perforated covering that is placed over a speaker baffle to protect the speaker drivers and make the speaker more aesthetically pleasing while allowing sound waves to pass through freely.
Ground lifter.
Balanced line adapter that passes the audio signal but has the ground wire discontinuous. By not passing the ground signal it stops hum from getting into the audio wires.
GUI (Graphical User Interface).
Technique used to display information on a television screen or other display device in order to make the operation of some equipment easier or provide enhanced functions.

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