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GRANBY TV

GLOSSARY

 

This glossary is a reference guide to the technical terms used on this site which may describe televisions, monitors, and other electronic equipment offered here.

 

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 
 


3


3:2 Pull-Down: 3:2 pull-down converts film footage to NTSC video. Film footage is shot at 24 frames per second (FPS) and NTSC video is shot at 30 FPS. 3:2 pull-down refers to the electronics needed to convert 24 FPS to 30 FPS so that it can be viewed on a NTSC video device. To accomplish this, 4 frames of film are converted to 5 frames of video by inserting an extra field of film frame every other frame:

 

Video Frame 1 2 3 4 5
Video Field a b a b a b a b a b
Film Frame 1 2 3 4


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A


a-Si: "Amorphous Silicon"
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Active Matrix: Term used to describe LCD Displays which have micro-transistors that "open" and "close" each pixel.
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Active Matrix TFT: A common type of LCD used in laptops, cameras, and LCD projection panels that were produced in the late 1980s to early 1990s. A typical active matrix TFT display is a single panel of LCD glass that controls all three primary colors. TFT displays are noted for their quick response time and their ability to display full motion video and animations without image ghosting.
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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 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. There are two methods used by the projection industry: 1) Full On/Off contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. When comparing the contrast ratio of projectors make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector.
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ANSI Lumens: ANSI lumens is a measurement of the overall brightness of a projector. Because the center of a projected image is brighter than the corners, ANSI lumens is a the most accurate representation of the image brightness. ANSI lumens are calculated by dividing a square meter image into 9 equal rectangles, measuring the lux (or brightness) reading at the center of each rectangle, and averaging these nine points.
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Aperture: In television optics, it is the effective diameter of the lens that controls the amount of light reaching the photoconductive or photo emitting image pickup sensor.
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Aperture Correction : Compensation for the loss in sharpness of detail because of the finite dimensions of the image elements or the dot-pitch of the monitor.
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Aspect Ratio: Aspect ratio is the ratio of the width of an image to its height. For example, a projector with a 16:9 aspect ratio will produce an image that is 16 units wide for every 9 units high. This is also referred to as 1.78:1 meaning the width is 1.78 times the height. For example, if you want an image 40 inches high then you need a screen that is at least 40 * 1.78 inches wide or 71 inches. Other common aspect ratios are 3:2, 4:3 and 5:4.

Native aspect ratio refers to the aspect ratio of the physical displays built into the projector. For example, a 1280 x 720 pixel display has a 16:9 native aspect ratio. A display that is 640 x 360 pixels is also a 16:9 aspect ratio, but with a fourth of the resolution of the other display.

Nearly every projector today will support multiple aspect ratios; however each manufacturer must decide who their intended audience is and optimize the projector for that audience. This means each projector has a native aspect ratio that is optimized for specific viewing material. Images shown in native aspect ratio will utilize the entire resolution of the display and achieve maximum brightness. Images shown in other than native aspect ratio will always have less resolution and less brightness than images shown in native aspect ratio.
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ATA Rated Case: A case rated strong enough to be shipped by common carrier; freight lines, UPS, FedEx, etc. Most cases of this type are easily recognized by their metal reinforced corners and handles. These cases are often referred to as "Anvil cases" bearing the name of one of the manufacturers.
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Auto Balance : A system for detecting errors in color balance in white and black areas of the picture and automatically adjusting the white and black levels of both the red and blue signals as needed for correction.
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B


Back Room Projector: A projector with a "long-throw" lens designed to be used from the far back of the room, often in a projection booth, balcony, or back of an auditorium. Many typical projectors have third party lenses available for "long-throw" applications.
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Backlit: Refers to a remote control, or on projector control panel, that has buttons and controls that are illuminated. This is a major asset when using the projector in a darkened or semi-darkened room. Many projectors have backlit remote controls, while the number of projectors with backlit control panels is much smaller. As projectors have gotten brighter, room lights tend to stay on, so while nice, having backlit controls is no longer important to many users.
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Bandwidth: The number of cycles per second (Hertz) expressing the difference between the lower and upper limiting frequencies of a frequency band; also, the width of a band of frequencies.
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Brightness: The attribute of visual perception in accordance with which an area appears to emit more of less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.)
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C


Carry-on Case: Refers to a projector with carrying case that fits into the overhead bin or under the passenger seat of an airline. A projector case that does not fit these conditions will need to be checked as luggage, and ride in the cargo area of the airline. Make sure you have a good hard case when checking a projector as luggage. A projector is a delicate device that can have its LCDs misaligned when not handled properly.
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Chromatic Aberration: An optical defect of a lens which causes different colors or wave lengths of light to be focused at different distances from the lens. It is seen as color fringes or halos along edges and around every point in the image.
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Chromaticity: The color quality of light that is defined by the wavelength (hue) and saturation. Chromaticity defines all the qualities of color except its brightness.
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Chrominance: A color term defining the hue and saturation of a color. Does not refer to brightness.
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Coated Optics: A variety of materials are put on to high quality lenses for several reasons. One of the key reasons is to minimize the amount of light reflected back to the lamp, and the amount of ambient light that mingles with the focused light leaving t he lens. Generally good coatings can add 15% or more to the lenses brightness. Other coatings are used for filtering colors/
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Color Dynamics: "The whitest whites, reddest reds, etc." High color dynamics are a result of dynamic range/contrast ratio's. When we describe a unit as having excellent color dynamics, the practical description might be "rich colors, excellent definition, high contrast".
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Color Temperature: A method of measuring the "whiteness" of a light source. Metal halide lamps have very high temperatures compared to halogen or incandescent lights.
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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 analog 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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Compressed Resolution: Most projectors automatically accept images that are of greater resolution than the native (true) resolution of the projector. The resulting image is scaled to fit the native resolution of the projector using a variety of scaling algorithms. Not all projectors use the same compression algorithms; therefore, the quality of compression can vary. The nature of compression in a digital device means that some image content is lost.
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Compressed SVGA: Unlike CRT based monitors, LCD and DLP projectors only have one "true" resolution. Most projectors out there are VGA (640x480) resolution. To project an 800x600 image to a VGA projector, the original 800x600 signal must be compressed down to VGA. This is done by interpolating the data, and trying to best display all the information with only two thirds of the pixels (307,000 vs 480,000). The resulting image gives you the SVGA page size, but some sacrifice of image quality. For the vast majority of people with SVGA laptops or desktops, they will have more satisfying results, outputting VGA to a VGA projector.
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Compressed SXGA: Found on XGA projectors, compressed SXGA handling allows these projectors to handle up to 1280x1024 SXGA resolution. Most owners of XGA projectors that use the compressed SXGA are workstation users (SUN, SGI, IBM, HP...) The typical uses f or these workstations are medical, life sciences, engineering and so on.
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Compressed XGA: Found on SVGA projectors, compressed XGA handling allows these projectors to handle 1024x768 XGA resolution. How good the compressed XGA is on a given model is a key factor in the decision process for most people choosing an SVGA projector. This is true as the market shifts from SVGA laptops to those with XGA screens.
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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 color details and tolerate extraneous room light. There are two methods used by the projection industry: 1) Full On/Off contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. When comparing the contrast ratio of projectors make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector.
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D


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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Dichroic: A mirror or lens that reflects or refracts selective wavelengths of light. Typically used in projector light engines to separate the lamps "white" light into red, green, and blue light.
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Digital Light Processing (DLP): The commercial name for this technology from Texas Instruments (TI): The technology inside is often referred to as either "micro-mirrors", or DMD: It works this way: build a few hundred thousand tiny mirrors, and line them up in 800 rows of 600 mirrors each. Now attach a hinge to each of those 480,000 mirrors. Attach each of those 480,000 hinges to its own very tiny motor! Power each motor with electrostatic energy! The motors tilt their mirrors up to 20 degrees at incredible speeds. This allows the mirrors to modulate light from a lamp, and send the "modulated signal" out through a lens, on to a screen. The most amazing part of DLP micro mirrors, is the scale of size. The 480,000 mirrors (actually 580,000 are used), hinges and motors are packed onto a "wafer" a bit larger than your thumbnail.
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Distribution Amplifier: An amplifier used to maintain a clean noise free signal to the projector over significant distances. Even with good heavily shielded cables, range of video and computer signals is limited to a few dozen feet before noticeable degradation. In ceiling mount situations, where the wiring may pass along side or across electrical conduits, etc. a distribution amp may be needed with shorter distances. Many distribution amps can also split the signal into 2 or more amplified signals for driving multiple projectors, projectors and monitors.
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DTV: DTV refers to the three types of digital television including Standard Definition Television (SDTV), Enhanced Definition TV (EDTV), Nad High Definition Television (HDTV).
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Dual Scan Passive Matrix: Newer version of the original passive matrix technology, where the screen is controlled by two processing systems. A bit faster than "single scan," response is still horrendously slow, they cannot do multimedia or video either. Contrast remains terrible. Dual scan is used in the least expensive LCD panels.
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DVI: DVI means Digital Visual Interface. DVI is a standard that defines the digital interface between digital devices such as projectors and personal computers. For devices that support DVI, a digital to digital connection can be made that eliminates the conversion to analog and thereby delivers an unblemished image. Click for more details on DVI. Specifications on DVI are available at www.ddwg.org.
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E


EDTV: EDTV stands for extended definition television and is a class of digital television (DTV) that refers to the 480p format. 480p is a progressive scan video format that produces a full frame of 480 lines of video.
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F


Fader: The control on a projector, that allows you to control the balance of sound between the projectors internal speakers and the external speakers (PA, powered speakers). Only a couple of projectors offer this convenient feature.
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Field: One half of a video frame consisting of either all of the even-numbered scanlines or all of the odd-numbered scanlines in a frame.
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FM Based Remote: A remote control that broadcasts its instructions with an FM transmitter, normally required in large rooms, thanks to long range, and no line of site requirement.
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Focal Length: The distance from the surface of a lens to its focal point.
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Form Factor: A general description, a major feature, or features that identify a type of projector or catagory of capabilities. Example: The Epson's form factor is considered the classic road warrior machine; weight under 17 lbs, zoom lens for easy placement, enough brightness to handle a darkened auditorium, and small enough to be moved easily and qualify as carry-on luggage, even in its hard case.
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Front Room Projector or Position: A unit that sits close to the screen, its short throw lens projects an image size that is about the same as the distance to the screen. 6FT diag. screen = 6FT distance. Generally the unit might be as close as 3/4 the screen size or as far as 1.2 times image size.
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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. There are two methods used by the projection industry: 1) Full On/Off contrast measures the ratio of the light output of an all white image (full on) and the light output of an all black (full off) image. 2) ANSI contrast is measured with a pattern of 16 alternating black and white rectangles. The average light output from the white rectangles is divided by the average light output of the black rectangles to determine the ANSI contrast ratio. When comparing the contrast ratio of projectors make sure you are comparing the same type of contrast. Full On/Off contrast will always be a larger number than ANSI contrast for the same projector.
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FXL: The most popular halogen lamp in use in lower cost projectors and overhead projectors. The lamps typically last about 40 hours, however for convenience, most projectors using halogen lamps carry a spare, and a quick method of going to the b ackup lamp. Metal halide lamps and UHP lamps are used in most of the medium and higher priced, more powerful portables.
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H


Halogen Lamps: Used in most low and medium priced projectors, these lamps last about 40 hours, with consistant output throughout their life. Although halogens look very white compared to a normal incandesent lamp, they are not as white as metal halide unit s. Cost of operation: Under $0.50 per hour. Most projectors using halogen lamps carry a spare lamp inside.
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Hard Wired Remote: Generally a remote control is wireless, and uses infra-red transmitter. There are situations where this is not practical: Large rooms where the speaker is 35 ft or more from the projector. Rear projection, where the screen will pass some signal, but normally has the presenter pretty much tied down. Also, the presenter has to point the remote "at" the projector which often means turning away from the audience. A couple of projectors (Epson for one) offer wireless remotes that will accept a cable (hard wiring) back to the projector, assuring range and signal getting though.
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HDCP: HDCP (High-bandwidth Digital Content Protection) is a method for protecting copyrighted digital content that uses the DVI (Digital Visual Interface) or HDMI (High-Definition Multimedia Interface, previously known as DVI-CE) by encrypting its transmission between the video source such as a set-top box, DVD player, or computer and the digital display device such as a projector, monitor or television. To view digital HDCP protected content, both the sending and receiving device must support HDCP.
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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 monitors such as a digital projector or digital television (DTV). HDMI is backward compatiable with DVI 1.0 specification and supports HDCP.

HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio, and interactive controls on a single cable. It transmits all ATSC (Advanced Television Systems Committe) HDTV standards and supports 8-channel digital audio. First product releases using HDMI occurred in 2003.
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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 me tal foil screens (some polarized), and certain glass bead screens. Prices and performance vary tremendously.
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I


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. The presenter must pay attention to where the remote is pointed. Some projectors have a IR sensor in both the front and rear of the projector, which can help a bit. When working at or near the maximum distance pointing right at the receiver is necessary. Remember "line of sight" - a person's head, directly between your remote and the projector may be enough to render it unusable. FM (radio frequency remote mousing systems, by comparison, have two distinct advantages, no line of sight requirement, and longer range.
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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. When the image is delivered to a video device such as a television, the odd and even fields are delivered at 50 or 60 fields per second and your eye sees an integrated image.
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International Power Supply: A unit that can operate under a international selection of power requirements. The specs of units vary widely, but the minimum is 105-230 volts, and 50-60 cycles AC (alternating current). If you see a specification like 110v, 220v instead of a range, those ratings are usually +/- a given percent such as 10%. Some units are "self-switching" they will automatically switch to whatever power source you plug it into. Others will have to be switched (internally or externally to accommodate a difference volt age or cycle range.
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Invert Image: Invert image flips the image from top to bottom, to compensate for ceiling mounting a projector upside down. Projectors typically ceiling-mount upside down, because most have "keystone" correction built in to compensate for the distortion created by "pointing up" from the table to the screen. Usual positioning has the projector about even with the bottom of the screen in a "table top position," or, even with the top of the screen when ceiling mounted.
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IR Communication Standard: Many new laptops have an Infra-Red transceiver that follow a recent standard for wireless communicating with peripherals (new laser printers complying with the standard) and networks or desktop systems. If you have a laptop like this, you know the pleasure of walking into a room with a configured laser printer, and printing out documents without having to "plug-in." Only a couple of projectors are now shipping that follow this standard. This allows their remote controls to talk directly to your laptop for remote mousing. A tremendous new capability, as you are normally much closer to your computer than the projector in medium or large rooms.
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K


Keystone: Keystoning occurs when the projector is not perpendicular to the screen, thereby creating an image that is not rectangular.
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Keystone Correction: Keystone correction makes a projected image rectangular. This can be accomplished by positioning the projector to be perpendicular to the screen. Since this is not always possible, most projectors are equipped with keystone correction that allows the image to be keystone corrected (made rectangular) by adjusting optics, making mechanical adjustments, or applying digital correction to the image. Keystone correction can be one or two dimensional and manual or automatic depending on the projector and the manufacturer.
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L


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. Excellent for pointing to objects or text, to make a point.
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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 all lens shift mechanisms are motorized with vertical lens shift being the most popular. With a projector that has lens shift you can optically correct for keystone distorted images. It is also used to help geometrically align images when stacking projectors.
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Letterbox: A method of preserving the originally aspect ratio of a production when presented on a projector with a different aspect ratio. This is accomplished by showing the full image and black where no image exists.
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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 a projection booth in the back of a theater, 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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Lux: A standard for measuring light, numbers provided by manufacturers usually do not provide necessary additional information to compare one product to another.
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M


Maximum Distance: Sometimes, rarely, 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. Generally this is very subjective. One projector might quote a distance that allows them to produce a 25FT diagonal image, while another, brighter projector might quote a distance that only equates to a 20FT image. Beware!
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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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Maximum Resolution: Maximum Resolution refers to the highest resolution that a given projector can display. If the Maximum Resolution exceeds the Native Resolution, the image is usually scaled to match or approximate the Native Resolution of the projector. Scaling reduces the image resolution and produces some artifacts in the image that are more apparent when viewing text than graphics or video.
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Menu Driven: Refers to the type of controls on a projector. A typical menu driven system, will first offer a menu of major catagories such as Computer, Video, Audio, Display, Options. After selecting Computer, you will get another menu of choices with items like brightness, contrast, number of colors, color balance, sync. Select one of those and you can then adjust it. Many projectors which are menu driven, also offer the most widely used functions in a non-menu fashion, such as have separate buttons on the remote for volume, brightness, and contrast, as well as switching between channels/sources.
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Metal Halide Lamp: The type of lamp used in many medium and all high end portable projectors. These lamps typically have a "half-life" of 1000-2000 hours. That is they slowly lose intensity (brightness) as they are used, and at the "half-life" point, they are half as bright as when new. These lamps output a very "hot" temperature light, similar to mercury vapor lamps used in street lights. Their whites are "extremely" white (with slight bluish cast.) and make Halogen lamp's whites look very yellowish by comparison.
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Mid Room Projector: Designed to sit not too close or far from the screen, for a 10FT screen, typical placement is 12.5 to 25FT away. Most mid-room projectors have zoom lenses.
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Minimum Distance: The closest position that a projector can focus an image onto a screen.
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N


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. Projectors are capable of projecting greater or smaller resolution images into the same physical resolution through scaling. Scaling reduces the resolution of larger images and increases the resolution of smaller images to match the native resolution of the display device. This type of digital scaling always produces some artifacts in the image that are more apparent when viewing text than graphics or video. Maximum Resolution, as mentioned in the projector specs at ProjectorCentral, refers to the largest resolution that the projector can scale to fit the Native Resolution.
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NTSC: The United States standard for video and broadcasting and is also used in the western hemisphere, Japan, and other Asian countries. NTSC standards are 525 lines of resolution transmitted within a 6MHz channel at 30fps.
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O


OHP: The common abbreviation for overhead projector.
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Overhead Projector (OHP): A device consisting of a light source, a transmissive or reflective platform, and a focusable lens assembly. An OHP is designed to project images from tranparencies onto a screen. LCD projection panels are designed to be used with transmissive OHPs and work best with OHPs that produce at least 3,000 lumens. Since 5% to 10% of the light that shines through an LCD panel gets onto the screen, a 3000 lumen OHP will produce an image of 150 to 300 lumens. Transmissive OHPs are fairly bulky (bigger than many projectors). Reflective OHPs are fairly portable but are not useful with LCD projection panels.
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P


PAL: A European and international broadcast standard for video and broadcasting. Higher resolution than NTSC.
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Panel: Also known as a projection panel, LCD projection panel, or plate. The panel is the predecessor of today's projectors. It is slightly larger and heavier than a notebook computer and the LCD it uses to produce an image is very similar to that of the notebook computer. Because panels lack their own light source, they are designed to sit on top of a transmissive overhead projector (OHP). (See the definition of Overhead Projector for lumen performance.) Because of its small size, low cost, and versatility, panels have been a popular solution for education applications where an OHP is frequently available in the classroom for other instructional purposes. A few products have been built that integrated the panel and the OHP. These were some of the earliest projectors.
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PanelLink: An all digital interface used to transmit computer video from a PC/Notebook to a projector. Supports resolutions from 640x480(VGA) up to 1600x1200(UXGA). This digital interface might someday replace the analog VGA interface typically used to connect projectors to computers.
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Passive Matrix LCD: The original LCDs, these are controlled by a single processing system, for the whole screen, unlike active and poly-si, which have descrete circuits for each "pixel." This results in a panel with terrible color dynamics and contrast (typically 15:1). They are also incredibly slow: On passive laptop computers, the cursor (or anything else) moving on the screen, goes invisible until you stop moving it (submarining) Only one or two projectors use any type of passive matrix display.
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Poly-Si (silicon) LCD: A popular LCD technology for the top of the line LCD projectors. Monochrome Poly-Si LCDs are typically placed in each of the three color light paths inside a projector, one each for Red, Green, and Blue. This results in increased color saturation, with contrast ratios above 200:1. Poly-Si technology is also a bit faster than the Active Matrix TFT, for smooth video and multimedia.
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Power 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. Progressive scan is used by projectors, computer monitors, some TVs and HDTV systems, and some digital camcorders.
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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. There are hundereds of products available in the market and they are differentiated by their resolution, performance and features. These devices attached to a computer or video device as you would connect a monitor.
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Q


QXGA: QXGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. 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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R


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. Good rear projection screens actually produce brighter images than some standard screens. So as not to waste space behind the screen, ideally a projector with a short throw lens is used. Since the projector can be placed even with the middle of the screen, without blocking anyone's view, keystoning is not a problem. Some mid-room projectors like the Epson have available 3rd party short throw lenses. Since the image is projected through the screen, the image must be reversed.
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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; the normal type of monitor used with computers, examples of usage: RGB input or output often referred to as Computer input or output.
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S


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(color, C). S-Video is also refered to as Y/C. A composite signal, typically found coming out of an RCA jack on the back of most VCRs has the Y and C information combined into one signal. The advantage of having luminance and chrominance separated is that a comb filter is not needed inside the video projector to separate the composite signal into the luminance and chrominance signals. A comb-filter can reduce the sharpness of your video image.
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SDTV: SDTV stands for standard definition television and is a class of digital television (DTV) that 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. The first field includes the odd lines and the second field includes the even lines.
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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. A typical short throw lens might produce a diagonal image size of 10 FT, from a distance of 7 to 10 FT.
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sRGB: sRGB stands for screen Red Green Blue and is a proposed standard for rendering color evenly across a variety of platforms. One objective is to replace the Web-safe palette of 216 colors with sRGB.
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SVGA: SVGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. 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 dots that a display uses to create an image. These dots are called pixels. 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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T


TFT: Thin Film Transistor
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U


UXGA: UXGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. 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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V


VGA: VGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. 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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W


Wi-Fi: Wi-Fi is Wireless Fidelity and is based on the IEEE 802.11 specifications for wireless local area networks (WLAN) developed by a working group of the Institute of Electrical and Electronics Engineers (IEEE). There are four specifications in the family: 802.11, 802.11a, 802.11b, and 802.11g. All four use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.
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Wi-Fi (802.11a): An IEEE specification for wireless networking that operates in the 5 GHz frequency range (5.725 GHz to 5.850 GHz) with a maximum 54 Mbps data transfer rate. The 5 GHz frequency band is not as crowded as the 2.4 GHz frequency, because the 802.11a specification offers more radio channels than the 802.11b. These additional channels can help avoid radio and microwave interference.
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Wi-Fi (802.11b): International standard for wireless networking that operates in the 2.4 GHz frequency range (2.4 GHz to 2.4835 GHz) and provides a throughput of up to 11 Mbps. This is a very commonly used frequency. Microwave ovens, cordless phones, medical and scientific equipment, as well as Bluetooth devices, all work within the 2.4 GHz frequency band.
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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 dots that a display uses to create an image. These dots are called pixels. 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 dots that a display uses to create an image. These dots are called pixels. 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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X


XGA: XGA is used to define a specific display resolution. Resolution is defined by the number of individual dots that a display uses to create an image. These dots are called pixels. 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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Z


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 projector 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 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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