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Technical jargon is all very well if you're in the know, but if you're not familiar with the terms being used, buying new equipment can be daunting. This guide is to help de-mystify some of the jargon, technology and features.

Ambient Light:
Any light in the viewing room created by a source other than the projector or screen.

Aspect Ratio:
The ratio of height to width of a frame or screen. In a 4:3 aspect ratio, the width of the image is 4/3 times the height. Most current TV and computer video formats are in a 4:3 aspect ratio. A 15 inch monitor is 12 inches wide by 9 inches high (9*4/3 = 12). A resolution of 640x480 is a 4:3 format (480*4/3 = 640). SXGA is a 5:4 aspect ratio is (1280x1024), HDTV is 16:9 for that movie theater feel, and 35mm slides are 3:2.

Aliasing:
Jagged edges along the outer edge of objects or text. Anti-aliasing refers to software adjustments that correct this effect. This effect is created by inadequate sampling techniques in computer-produced images.

Backlit:
A remote control, projector control panel, or other object illuminated from behind.

Bandwidth:
The frequency range of a particular transmission method. In video systems, this value is expressed in MHz, and the better the signal, the greater the bandwidth required.

Bit Mapped Graphics:
The type of graphic that is defined and addressed on a bit-by-bit basis which makes all points on the screen display directly accessible.

BNC:
Used with coaxial cables, this connector receives all R, G, B, H-Sync and V-Sync information, and composite video.

CD:
CD stands for Compact Disc.

CD-ROM:
CD stands for Compact Disc, the ROM part means Read Only Memory. A CD-ROM is read only, nothing can written to the disc and no amendments can be made to existing content.

Colour Temperature:
A method of measuring the "whiteness" of a light source. Metal halide lamps produce higher temperatures than halogen or incandescent lights.

Colour Resolution:
The total number of colors available, expressed in bits per pixel.

Component Video
Component video is a type of video information that is transmitted or stored as two or more separate signals (as opposed to composite video, such as NTSC, PAL, which is a single signal).
Most component video systems are variations of the red, green and blue signals that make up a television image. The simplest type, RGB, consists of the three discrete red, green and blue signals sent down three wires, usually accompanied by one or two synchronising signals on additional wires. This type is commonly used in Europe through SCART connectors. Outside Europe, it is generally used for computer monitors, but rarely for TV-type applications.
S-Video is also considered a component signal, because the luminance and chrominance Chrominance (color) signals are transmitted on separate wires.

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.

CRT:
CRT refers to traditional 'tube' based televisions. The CRT stands for Cathode Ray Tube.

Diagonal Screen:
One corner of a screen to the opposite corner. A 9FT high, 12FT wide, screen has a diagonal of 15FT. If the screen is 12x12, it would still rate 15FT diagonal since that would be the diagonal usable.

Digital Light Processing (DLP):
Developed by Texas Instruments, DLP is a light processing system that utilized hundreds of thousands of tiny spinning mirrors to reflect images. Many feel it is the most accurate reproduction of color and images available today.

Dot Pitch:
The distance between the dots on a CRT display. The closer together the dots are create a higher resolution of a displayed image.

Dithering:
Making digital images appear smoother by adding color or random noise during the digitization process.

DNR
Stands for Digital Noise Reduction. Is a feature built into many TVs and VCRs, plus high-end DVD players, that seeks to reduce grain from tapes and terrestrial broadcasts received via imperfect aerials.

DVB
Stands for Digital Versatile Broadcasting. Is a set of standards which define MPEG2 terrestrial and satellite digital broadcasting. Both the UK's digital terrestrial signal and Sky digital are DB-compliant.

DVD
Stands for Digital Versatile Disc. Is a high-density storage medium that can be used to store video (DVD-Video), audio (DVD-Audio) and computer data (DVD-ROM). Most DVD-Audio movies are single sided, dual-layer discs, with a capacity of 4.7GB.

DVD-RAM, DVD-RW, DVD+RW
Are the re-recordable modes of the three domestic DVD recording formats.

DVI
Digital Visual Interface.

Flat Screen (CRT):
A CRT screen made more flat than a standard tube by using more than one electron gun to create concise reproduction and greater detail.

Flatscreen or Flatpanel screen:
A general reference, commonly used to describe Plasma or LCD flatscreens.

Focal Length:
Focal length is the distance between the lens and its focal point. A smaller focal length indicates a wider-angle lens.

Genlock:
Synchronizing signals between two video sources, which is necessary when overlaying computer graphics on an image from VCR, camera, or videodisc player.

Ghosting:
A shadow or weak secondary image as seen on a monitor or display which is created by multiple path broadcast transmission errors.

High Gain Screen:
A screen that uses one of more methods to collect light and reflect it back to the viewing audience, which will increase the brightness of the image over a white-wall or semi-matte screen.

H Sync:
H Sync stands for Horizontal synchronization. A marker, which indicates to a computer or video signal that it, is the beginning of a line.

HDTV:
HDTV means High Definition Television. High definition, wide-screen television broadcasting with digital audio.

Horizontal Frequency:
Also referred to as kHz, the total number of horizontal lines scanned per second in a displayed image.

Horizontal Resolution:
The total number of vertical lines individually perceived across the horizontal rows of a monitor.

Hz:
Hz is an abbreviated form for Hertz. A measure of frequency in cycles per second. Used to express the frequency of an electrical signal or event.

Invert Image:
Many projectors that are ceiling mounted are mounted upside down. Invert image corrects the image digitally so your projected image is not also upside down.

Interlacing:
Technique used to reduce flicker caused when the first created video field fades while the next is being written.

JPEG:
AKA Joint Photographic Experts Group. An international group, which is working, on a proposed universal standard for the digital compression and decompression of still images used in computer systems. The JPEG idea reduces image size as much as 65:1 and still maintains image integrity by getting rid of subtle color differences the human eye can not see.

Keystone Correction:
A projectors ability to correct the effects of “pointing up” or “pointing down” at a screen enabling the projector user’s audience to view a rectangular image rather than one with a wider top or bottom.

Keystoning:
The distortion (usually a wide-top narrow-bottom effect) of a projected image caused by a projector "pointing up" or "pointing down" at its screen. Named after its similarity in shape to the keystone used in constructing an arch.

LCD:
LCD stands for Liquid Crystal Display. This technology comes in many forms, sizes, and resolutions. Its primary purpose is to present a digital image for viewing. They are used in many notebook computer displays and also used as technology inside a projector to project high-resolution digital images.

Lenticular:
A screen surface that has an embossed geometric shaped pattern that affects view/angle performance and reflection of ambient light.

Long Throw Lens:
A lens designed for projection from the back of a room. Long throw lenses would be used a projection booth in the back of a theater, or from the back of a large classroom. A long throw lens would have to be 50 to 100 FT back to project a 10FT diagonal image.

Macro Lens:
A lens that provides continuous focusing from infinity to extreme close-ups, often to a reproduction ratio of 1:2 (half life-size) or 1:1 (life-size).

Metal Halide Lamp:
The type of lamp used in most high-end portable projectors. These lamps output a very "hot" temperature light, similar to lamps used in streetlights. Metal Halide whites are super white (with a hint of blue) and make Halogen lamp white very yellowish by comparison.

MPEG:
Stands for Motion Picture Experts Group. Is a set of 'lossy' compression standards. With MPEG, information regarded as unimportant (i.e imperceptible to the viewer or listener) is irretrievably discarded by means of a highly complex mathematical process. The data rate is considerably reduced, though. MPEG1, as used on Video CDs, is a low bit rate variant capable of VHS quality. MPEG2 works at faster bit rates, and can yield high quality results-as demonstrated by DVD and DVB.

Multimedia Presentations:
The integration of text, art, graphics, photography, animation, audio, and video into presentations.

Multiplexing:
The condensing of many signals into a few or one signal that still represents all of them. An LCD panel performs the de-multiplex function. It takes video signals that contain whole frames of video data and displays them as individual signals on each pixel.

NTSC:
It is named after the National Television System(s) Committee, America’s industry-wide standardization body that created it. It is actually a lower resolution than systems used here, the UK has the PAL broadcast standard. Currently however, the advent of HDTV and digital has had a greater take up in northern America.

Network:
Allows two or more computers or devices to exchange information quickly and easily. A wireless network does the same thing using radio signals or infra-red beams for example to relay information without the use of cables.

Output:
Material that a device generates from its memory for display on a monitor or screen. Alternatively for transfer to other media, such as paper or a storage device such as DVDs, CD-ROMs or Memory Cards.

PAL:
PAL stands for Phase Alternation by Line. The standard color system used throughout Western Europe, except in France.

Pixel:
Short for picture element. The smallest element in a displayed image. A color pixel is a combination of red, green and blue subpixels. Total pixels are usually expressed in horizontal x vertical dimensions (e.g. 640 x 480).

Power Zoom:
A zoom lens with the zoom in and out controlled by a motor, usually adjusted from the control panel or a remote control. This is as compared to Digital zoom, which does this same function Digitally.

Projection Axis:
Direction of the "imaginary" line that extends from the center of the projection lens through the center of the screen.

RGB:
Red, Green, Blue; the type of monitor generally used with computers. RGB input or output often referred to as Computer input or output.

RCA connector:
The connector used with VCRs and stereos for composite video signals and audio.

Real Time:
The transfer of data that returns results so quickly that the process appears to be instantaneous.

Rear Projection:
Projecting an image through a translucent screen material for viewing from the opposite side. This method of projection is also an option for home theater use in large spaces.

Regional Coding
Eight global DVD regions exist therefore a disc sold in one won't play in a player intended for another. The UK is in Region 2 (R2) but many people want Region 1 (the US) discs, which are cheaper and have better features. Thus, many DVD players here can be made multi-region by handset hacking or can be modified by a dealer.

Resolution:
Number of pixels (or dots) per unit of area, measure in number of pixels wide by the number of pixels high that can be displayed on the screen or monitor. More pixels per unit of area produce a higher resolution.

Scart:
SCART (from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) is a French-originated standard and is a 21-pin AV connector which can carry composite, S-video and RGB video, plus stereo audio and widescreen/4:3 switching signals. Also called Péritel (especially in France, where the SCART word is not normally used) and Euroconnector. SCART makes it easy to connect VCRs, DVD, gaming systems and other equipment to television sets with optimal quality.

SECAM:
The French broadcast standard (used in some other international markets) for video and broadcasting. Like PAL, SECAM is also a higher resolution than that of NTSC, America's broadcasting standard.

Simulated colour:
Also known as "false colour," or "colourised." Projected colours that are not the same as the original image. Some products use a single, colourised LCD, often with purple for dark shades and yellow for light shades (purple background/yellow foreground). Therefore, what should appear on a screen as blue may be yellow, green may be purple.

S-Video:
S-Video - A video format offering a higher quality signal than composite video, but a lower quality than component video. This mid-level format divides the signal into two channels - luminance and chrominance.

TFT:
AKA Thin Film Transistor. A technology used to make Active Matrix LCD panels wherein each pixel has its own transistor switch.

Throw Distance:
Length of the projection beam required for a projector to produce and image of a desired size.

THX
Cinema systems bearing the 'THX' logo comply with stringent performance parameters set by Lucas Film. Software can also be THX-approved. Two domestic variants also apply, THX Ultra, which applies to high-end home cinema equipment and THX Select, for midrange gear.

V-Sync:
AKA Vertical synchronization. A marker in a video signal for the beginning of a frame.

Varifocal Lens:
A projector lens that has three focal elements contained in a single assembly.

Vertical Resolution:
The total number of horizontal lines that can be perceived in the vertical direction of the screen.

VHS:
VHS stands for Video Home System, and is the video standard which came to prominence, phasing out other standards such as Betamax.

Zoom Lens:
A lens with a variable focal length. This translates to being able to adjust the size of the image on a screen by adjusting the zoom lens, instead of Audio Visual Innovationsng to move the projector closer or further.