Glossary -G-
Gain — 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 — Amplification of a circuit.
Gain — Camera adjustment which controls the strength of the camera’s video signal, altering contrast and brightness of the picture.
Gate — Audio device that permits audio to pass through or mutes it electronically, depending on some criteria such as how loud the sound is.
Gated mixer — Audio mixer that senses when someone is speaking into one mike and shuts down the other mikes to reduce noise and echo.
Gel — Colored material that looks like cellophane and can be placed in front of a lamp to color the light. Usually the flimsy gel material is held in a frame which fits the fixture’s scrim holder.
Genlock — Ability of a camera or other TV device to receive an external video signal and synchronize its own video signal to it, so the two videos can be neatly switched or mixed.
Genlock — Electronic device which, when fed a video signal, will manufacture synchronized sync signals so that (1) its picture will synchronize with the source’s video signal or (2) its sync signals will help other devices (like cameras) synchronize themselves with the source’s video signal.
Geosynchronous or geostationary satellite — A satellite (usually for domestic communications or TV) whos position is constant relative to a point on the earth. An orbit of 22,300 miles above the equator causes the satellite to circle the earth at the same speed the earth rotates.
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 colors. There are variations for animation sequences and for text.
Gigahertz (GHz) — One billion Hertz (Hz) or one billion cycles per second. Domestic satellites transmit at frequencies above 3.7GHz.
Glow — 2-D graphic effect where a selected object appears to glow.
Gobo — Patterned cutout used to cast a shadow with a design on a surface, like tree branches or venetian blinds. Works like a cookie, but without a special projector.
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.
Gradient background — A background that goes smoothly from light to dark, or one color to another, typically used behind titles.
Graduated filter — Lens filter that’s part clear and part colored or dark, making perhaps 1/2 of the picture dark.
Graphic equalizer — Electronic audio device that cuts or boosts particular sound frequencies passing through it.
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.
Gray scale — A standard of 10 steps from black to white used to measure contrast ratios. To be visible on TV, objects must be at least 1 gray scale step different in brightness from their backgrounds.
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.
Group — A combination of signals from a mixer. Several inputs, assigned to a group, are all controlled together and go to that group’s output in the mixer. The left channel, for instance, is a group in a stereo mixer.
GUI — (Graphical User Interface) Software that presents the computer user with a screen with icons and menus that are simple, intuitive, and visually appealing.
Gyroscopic error — Sideways bending or breakup of the TV picture as it plays back, caused by movement of a VCR while it was recording the picture.
Gyrozoom — Gyro stabilized zoom lens used with professional cameras to steady pictures.
