Glossary of AV terms

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Anamorphic Lens

An anamorphic lens is a lens that has different optical magnification along mutually perpendicular radii.
This provides the ability to project a source image of one aspect ratio, such as 4:3, into a different aspect ratio, such as 16:9, by using different magnifications for the horizontal and the vertical dimensions of the projected image.
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ANSI lumens

Brightness is measured in ANSI (American National Standards Institute) lumens: the brighter the projector, the higher the ANSI lumen rating.

The lumen rating is the average measurement achieved by recording brightness at a number of different points within the light source. It is the fairest and most accurate indication of a unit's overall brightness.
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Aspect ratio

Aspect ratio is the ratio of the width of an image to its height.
The most popular aspect ratio is 4:3 (4 by 3). Early television and computer video formats are in a 4:3 aspect ratio, which means that the width of the image is 4/3 times the height.

Examples: A 15 inch monitor is 12 inches wide by 9 inches high (9 x 4/3 = 12). A resolution of 640x480 is a 4:3 format (480 x 4/3 = 640). Other formats are 5:4 used by the 1280x1024 SXGA resolution, 16:9 is used by HDTV, and 3:2 for 35mm slides
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Brightness

The attribute of visual perception in accordance with which an area appears to emit more or less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)
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Colour Dynamics

"The whitest whites, reddest reds, etc." High colour dynamics are a result of dynamic range/contrast ratio's. When we describe a unit as having excellent colour dynamics, the practical description might be "rich colours, excellent definition, high contrast".
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Component Video

Component Video is a method of delivering quality video (RGB) in a format that contains all the components of the original image.
These components are referred to as luma and chroma and are defined as Y'Pb'Pr' for analogue component and Y'Cb'Cr' for digital component. Component video is available on some DVD players and projectors.
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Composite Video Signal

The combined picture signal, including Vertical and Horizontal blanking and synchronizing signals.
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Contrast Ratio

The ratio between white and black.
The larger the contrast ratio the greater the ability of a projector to show subtle colour details and tolerate extraneous room light.
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dB

dB or decibel is a measure of the power ratio of two signals.
In system use, a measure of the voltage ratio of two signals provided they are measured across a common impedance.
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DCDi

Directional Correlation Deinterlacing (DCDi) was developed by Faroudja and is a video algorithm designed to eliminate jagged edges that are generated by interlaced video.
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Diagonal Screen

The diagonal of a screen can be computed by squaring the width, squaring the height, adding them together and taking the square root.
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DLP

Digital Light Processing(DLP) is the commercial name for this technology from Texas Instruments (TI).
The technology inside is often referred to as either "micro-mirrors", or DMD.
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DTV

DTV refers to the three types of digital television including Standard Definition Television (SDTV), Enhanced Definition TV (EDTV), and High Definition Television (HDTV).
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DVI

 Digital Visual Interface(DVI).
The standard that defines the digital interface between digital devices such as projectors and personal computers.
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Focal Length

The distance from the surface of a lens to its focal point.
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Full On/Off Contrast

Contrast is the ratio between white and black.
The larger the contrast ratio the greater the ability of a projector to show subtle color details and tolerate extraneous room light.
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HDMI

HDMI (High Definition Multimedia Interface) is an uncompressed, all-digital audio/video interface that supports audio/video sources such as a set-top box, DVD player, A/V receiver, and video.
HDMI is backward compatiable with DVI 1.0 specification and supports HDCP.
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High Gain Screen

A screen that uses one of many methods to collect light and reflect it back to the audience, which dramatically increase the brightness of the image over a white wall or semi-matte screen. Technologies used include curved screens, special metal foil screens (some polarized), and certain glass bead screens. Prices and performance vary tremendously.
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Infra-red Remote

The traditional remote control, it transmits infra-red, like a television remote.
Typical range is limited to 30 or 35 feet. Infra-red requires line of site or a bounce off of a hard surface.
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Interlaced Video

Video systems in which each frame of video consists of two video fields.
The odd numbered lines are contained in the first field and the even numbered lines are contained in the second field.
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Invert Image

Invert image flips the image from top to bottom, to compensate for ceiling mounting a projector upside down.
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Keystone Correction

Keystone correction makes a projected image rectangular.
Keystone correction can be one or two dimensional and manual or automatic depending on the projector and the manufacturer.
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Laser Pointer

A small pen or cigar sized pointer, that contains a small battery powered laser, which can project a small, red (typically), high intensity beam of light that is immediately very visible on the screen.
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LCD

LCD stands for liquid crystal display and comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. A common use of LCDs is as a display on a notebook computer.
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Lens Shift

The Lens Shift feature of a projector allows the optical lens to be physically shifted up and down (Vertical) or left and right (Horizontal).
Most lens shift mechanisms are motorized with vertical lens shift being the most popular.
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Long Throw Lens

A lens designed for projection from the back of a room, or rather the back of a long room.
Long throw lenses would be used in a projection booth in the back of a theatre, etc.
A typical long throw lens might have to be 50 to 100 FT back to project a 10FT diagonal image.
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Maximum Distance

The distance from the screen that a projector can focus the image.
Most of the time, it is the manufacturer's opinion of how far from a screen the projector can be to cast an image that is useable (bright enough) in a fully darkened room.
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Maximum Image Size

The largest image a projector can throw in a darkened room.
This is usually limited by focal range of the optics.
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Native Resolution

Native Resolution refers to the number of physical pixels in a display device.
For example, an SVGA projector has 800 physical pixels of resolution horizontally and 600 pixels vertically or 480,000 total pixels. This is the native resolution of the projector.
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NTSC

The United States broadcast standard for video and broadcasting. An older standard and lower resolution than systems used in most of the world.
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OHP

The common abbreviation for Over Head Projector.
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PAL

A European and international broadcast standard for video and broadcasting.
PAL is a higher resolution than NTSC.
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Pixel

A small coloured dot that is one of many comprising the image.
These can just be seen when the screen is looked at very closely.
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Power/Electronic Zoom

A Zoom lens with the zoom in and out controlled by a motor, usually adjusted from the projector's control panel and also the remote control.
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Progressive Scan

A type of display in which all the horizontal lines of an image are displayed at one time in a single frame, unlike an interlaced scan in which a frame consists of two separate fields with the first field consisting of odd horizontal lines and the second field even horizontal lines.
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Projector

A projector is a device that integrates a light source, optics system, electronics and display(s) for the purpose of projecting an image from a computer or video device onto a wall or screen for large image viewing.
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QXGA

QXGA is used to define a specific display resolution.
A QXGA display has 2048 horizontal pixels and 1536 vertical pixels giving a total display resolution of 3,145,728 individual pixels that are used to compose the image delivered by a projector. A QXGA display has 4 times the resolution of an XGA display.
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Rear Screen Projection

Using an opaque screen, the projector is placed behind the screen, invisible to the audience.
It projects onto the screen and the audience sees it on the other side.
Ideally a projector with a short throw lens is used.  Since the image is projected through the screen, the image must be reversed.
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Resolution

The amount of pixels that make up an image - e.g. 640 x 480 means 640 pixel groups across the image by 480 pixel groups down.
The larger the number of pixels the higher the resolution and the sharper and more detailed the image is.
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Reverse Image

Reverse image is a feature found on most projectors which flips the image horizontally. When used in a normal forward projection environment text, graphics, etc, are backwards. Reverse image is used for rear projection.
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RGB

Red, Green, Blue.
Example of usage: RGB input or output often referred to as Computer input or output.
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S-Video

A video transmission standard that uses a 4 pin mini-DIN connector to send video information on two signal wires called luminance(brightness, Y) and chrominance(colour, C).

S-Video is also referred to as Y/C.
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SDTV

Standard Definition Television(SDTV) refers to the 480i format.
480i is an interlaced video format that produces a full frame of 480 lines of video in two successive fields.
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SECAM

A French and international broadcast standard for video and broadcasting.
Higher resolution than NTSC.
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Short Throw Lens

A lens designed to project the largest possible image from short distance.
Most front room projectors use short throw lens. They are often required for rear projection, where the depth behind the screen is limited.
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SVGA

SVGA is used to define a specific display resolution.
Resolution is defined by the number of individual pixels that a display uses to create an image.
An SVGA display has 800 horizontal pixels and 600 vertical pixels giving a total display resolution of 480,000 individual pixels that are used to compose the image delivered by a projector.
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SXGA

SXGA is used to define a specific display resolution.
Resolution is defined by the number of individual pixels that a display uses to create an image.
An SXGA display has 1280 horizontal pixels and 1024 vertical pixels giving a total display resolution of 1,310,720 individual pixels that are used to compose the image delivered by a projector.
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TFT

Thin Film Transistor(TFT)
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UXGA

UXGA is used to define a specific display resolution.
Resolution is defined by the number of individual pixels that a display uses to create an image. 
A UXGA display has 1600 horizontal pixels and 1200 vertical pixels giving a total display resolution of 1,920,000 individual pixels that are used to compose the image delivered by a projector.
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VGA

VGA is used to define a specific display resolution. Resolution is defined by the number of individual pixels that a display uses to create an image.
A VGA display has 640 horizontal pixels and 480 vertical pixels giving a total display resolution of 307,200 individual pixels that are used to compose the image delivered by a projector.
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WiFi

Wi-Fi is Wireless Fidelity and is based on the IEEE 802.11 specifications for wireless local area networks (WLAN).
WiFi was developed by a working group of the Institute of Electrical and Electronics Engineers (IEEE).
There are four specifications: 802.11, 802.11a, 802.11b, and 802.11g.
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WSXGA

WSXGA defines a class of SXGA displays with a width resolution sufficient to create an aspect ratio of 16:9.
Resolution is defined by the number of individual pixels that a display uses to create an image.
A WSXGA display has 1920 to 1600 horizontal pixels and 1080 to 900 vertical pixels respectively that are used to compose the image delivered by the projector.
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WXGA

WXGA defines a class of XGA displays with a width resolution sufficient to create an aspect ratio of 16:9.
Resolution is defined by the number of individual pixels that a display uses to create an image.
A WXGA display has 1366 to 1280 horizontal pixels and 768 to 720 vertical pixels respectively that are used to compose the image delivered by the projector.
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XGA

XGA is used to define a specific display resolution. Resolution is defined by the number of individual pixels that a display uses to create an image.
An XGA display has 1020 horizontal pixels and 768 vertical pixels giving a total display resolution of 783,360 individual pixels that are used to compose the image delivered by a projector.
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Zoom Lens

A lens with a variable focal length providing the ability to adjust the size of the image on a screen by adjusting the zoom lens, instead of having to move the projector closer or further.
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Zoom Lens Ratio

 Is the ratio between the smallest and largest image a lens can project from a fixed distance. For example, a 1.4:1 zoom lens ratio means that a 10 foot image without zoom would be a 14 foot image with full zoom. Conversely, a 10 foot diagonal image at 15 feet with no zoom would still be a 10 foot image at 21 feet at maximum zoom (15 x 1.4 = 21 feet). A zoom lens is "not as bright" as a fixed lens, and the higher the ratio, the less light output.
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