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

A    [ top ]

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.

ANSI Lumens:
ANSI stands for American National Standards Institute. It is a standard for measuring light output. Different lamps play a role on light output. Halogen lamps appear dimmer than another metal-halide, even if the two units have the same ANSI lumen rating. Type of LCD technology (active matrix TFT, Poly-Si, passive), type of overall technology (LCD vs. DLP vs. CRT), contrast ratios, among other factors can also affect the end result.

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.

B    [ top ]

Backlit:
A remote control, projector control panel, or other object illuminated from behind. This can be helpful when working in darkened rooms.

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.

Build Slide:
"Build series" slides show audiences where a topic is heading a line at a time. Each new line added appears in a bright color while previous the line drops back to a darker color.

Button:
A graphic element inside an interface that represents an embedded action or function.

C    [ top ]

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

Clip-Art:
Graphics that have been previously published which can be imported into a presentation simply by copying and pasting.

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

Compatible:
When different hardware or software can be used together without a major over-haul.

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.

D    [ top ]

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.

Desktop Videoconferencing:
Videoconferencing via personal computer.

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.

E    [ top ]

EGA:
AKA Enhanced Graphics Array, EGA is an image which displays 640 pixels by 350 lines with 16 colors from a palette of 64 colors.

F    [ top ]

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.

Flat Screen:
A CRT made more flat than a standard tube by using more than one electron gun. Beneficial to people who require concise reproduction and great detail such as graphic designers.

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

G    [ top ]

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.

H    [ top ]

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

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

Horizontal Frequency:
AKA 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:
AKA Hertz. A measure of frequency in cycles per second. Used to express the frequency of an electrical signal or event.

I    [ top ]

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.

J    [ top ]

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.

K    [ top ]

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.

L    [ top ]

LCD
AKA 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.

Laser Pointer:
A hand held device that emits a thin laser beam that focuses a bright dot (usually red) on projected images or just about anywhere. Used by presenters to direct the viewer's eye to a particular point of interest.

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.

M    [ top ]

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.

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.

N    [ top ]

NTSC:
The USA’s broadcast standard for video and broadcasting. It is actually a lower resolution than systems used in most of the world. However, by the year 2002 stations will be required to broadcast higher resolution video signals.

Network:
Allows two or more computers to exchange information quickly and easily.

O    [ top ]

Output:
Material that a computer generates from its memory for display on a monitor or for transfer to other media, such as paper or magnetic storage such as zip or floppy disks or a CD-ROM.

Overlay:
The capability to superimpose computer-generated graphics and/or text on motion or still video.

Overhead Projector (OHP):
An OHP is designed to project images from transparencies onto a screen.

P    [ top ]

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

Poly-Si (silicon) LCD:
A popular LCD technology for the top of the line LCD projectors, which results in increased color saturation, with contrast ratios above 200:1.

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.

Presentation Ergonomics:
The study and science of optimizing relationships between a presenter and the presentation environment.

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

R    [ top ]

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.

Remote Mouse and Keyboard Control:
Allows presenter complete control of computer presentation without direct access to projector. Allows for freedom of movement.

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.

RS-232C:
A cable that connects a computer and its peripherals.

S    [ top ]

SaBRE:
AKA Subtractive Bi-Refringent Effect, a technology that allows two panels rather than three to generate the full 16 color VGA palette. The top panel provides white, magenta, blue, and cyan; the second brings colors from white through yellow and to red.

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 the US, until 2002.

Simulated color:
Also known as "false color," or "colorized." Projected colors that are not the same as the original image. Some products use a single, colorized 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.

SVGA:
AKA Super VGA. Refers to a computer signal that is higher than the standard VGA resolution of 640 pixels by 480 lines with 16 or 256 colors. SVGA graphics cards may output resolutions such as 1024 x 768, 1280 x 1024, 1600 x 1200 pixels or higher, with 16.7 million colors displayed.

T    [ top ]

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.

TSTN:
AKA Triple Super Twist Neumatic. A technology used to make Active Matrix LCD panels wherein each pixel has its own transistor switch.

U    [ top ]

UXGA:

Resolution of a computer generated image. A UXGA projector will be able to display a 1600x1200 image from a computer running in a UXGA video mode. If the computer is not running in a UXGA video mode, typically the projector will resize the image to 1600 x 1200.

Uniformity

Uniformity is the percentage of brightness carried from corner to corner of your image. A higher uniformity percentage means better consistency of brightness throughout your image. For a more consistent image, look for projectors with 85% or better.

V    [ top ]

VGA Resolution:
VGA Resolution normally refers to a 640 x 480 pixel display, regardless of the number of colors available. Originally VGA was 640 x 480 16 colors.

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.

VGA:
AKA Video Graphics Array. This is the standard interface for the IBM PS/2. It is the only analog graphics card IBM has used (other cards handle digital information) 720 x 400 in the text mode, graphics mode 640 x 480 resolution.

Video Compatibility:
Ability of computers and projection units to transmit and receive data to read and/or project various video tape standards such as NTSC, PAL, SECAM and S-VHS.

W    [ top ]

Whiteboard:
Document-conferencing product that lets multiple users simultaneously view and make notes on a document with pens, highlighters and drawing tools.

X    [ top ]

XGA:
Acronym for Extended Graphics Adapter. A standard introduced by IBM that includes VGA as well as resolutions up to 1024 pixels by 768 interlaced lines.

Y    [ top ]

Y/C Connector:
A 4-pin DIN connector used for high-end S-video sources.

Y-Cable:
A cable that splits the monitor signal so that it will work simultaneously with both a monitor and a LCD panel.

Z    [ top ]

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 hAudio Visual Innovationsng to move the projector closer or further.

ASPECT RATIO: The ratio of height to width of a frame or screen.

What is a native aspect ratio and why does it matter?

In case you aren't familiar with the term, "aspect ratio" means the number of units wide by the number of units high of your display. A 4:3 display produces an image that is more square, and a 16:9 ratio produces an image that is more panoramic in shape.

There are currently two commonly manufactured native aspect ratios available for fixed display devices like DLP and LCD projectors, and Flat Panel TVs. Those two aspect ratios are 4:3 format (like the televisions and monitors most of us use) and 16:9 (also known as widescreen) format.

There are also two different broadcast standards for television (16:9 format HDTV and 4:3 format NTSC) in the United States. DVD media also comes in both widescreen and standard output options. Therefore, there isn't one obvious native resolution solution.

So how do I watch everything I want on a 4:3 or 16:9 projector or LCD TV?

Unless you limit the type of material to one aspect ratio or the other, there has to be a tradeoff with either the 4:3 or the 16:9 options.

The good news is that the tradeoff doesn't mean you can't watch what you want. It simply means you will see black bars on the top and bottom or along the sides of your image when viewing material that does not match the native resolution of your LCD TV or projector. But based on the type of entertainment you watch most frequently, you can make an informed decision about which is best for you.

Which aspect ratio is best for you?

For business uses such as PowerPoint™ presentations and viewing spreadsheets, 4:3 displays are still your best bet. You will still be able to take your projector home and watch movies on the weekends.

SHORT THROW VS. LONG THROW LENSES

You may have heard about throw distance before while researching projectors, but what does it mean to you? A common throw distance is one foot of screen for every two feet of space between projector and screen. That is a general rule for projectors with a standard lens. Projectors with short throw lenses are able to create larger images with less distance between projector and screen.

When is a short throw lens beneficial?

A short throw lens allows users to create the big picture they want, in a tight space. Projectors like the Hitachi S225 and X275 can project an impressive 60-inch diagonal image from just five feet away from the screen. Short throw lenses are commonly used in environments like these:

Small conference rooms Small classrooms Trade show booths Small home theaters

Tip: Projectors with quieter fans are desireable when using a projector in a smaller space.

Who makes short throw lenses?

Many manufacturers have short throw lenses as an option on selected projectors. However, some manufacturers include short throw lenses as a standard feature on specially designed projectors. Some projectors that ship with a short throw lens standard are:

• BenQ PB8220
• Hitachi CP-X275W
• NEC LT240K

What is the difference between a short throw and long throw lens?

While short throw lenses help create larger pictures from shorter distances; long throw lenses help create smaller, more viewable images from greater distances. A long throw lens is advantageous in large venues, particularly in fixed installations. Churches often require long throw lenses for worship spaces, because the projector is often mounted far away from the screen, behind the congregation. Without a long throw lens, the image would be too large.

What are zoom lenses?

Manual or digital zoom is a feature on many standard, long, or short throw lenses. The zoom feature allows for larger or smaller images from the same distance, much like a zoom lens on a 35mm camera.

Do short and long throw lenses cost more than standard lenses?

If a short or zoom lens is not standard on the projector you choose, and you have the need for one, an external lens may be an option for you. The cost of external lenses varies. They generally range from $1,500 to $4,000 dollars depending on the type of lens you need, and the projector model. Not all projectors can use external lenses, and in some cases adding one may void the manufacturers warranty. Ask a projector expert for details if you think an external lens is right for you.

RESOLUTION

Resolution is the number of pixels as measured from left to right and top to bottom of your image. Currently SVGA (800x600) and XGA (1024x768) are the most common projector resolutions. An XGA projector has about twice the number of pixels of an SVGA projector, but it will also cost a bit more.

We recommend a XGA, or a high resolution native widescreen formats like WXGA, as the best choice for HDTV, DVDs and other home theater applications.

There is more to image quality than just resolution. Brightness uniformity and the kind of screen you are projecting on are also key players in image quality.

BRIGHTNESS

How bright should my projector be?

Projector brightness is measured in ANSI lumens. DLP and LCD projectors come in various sizes and brightness to fit the various needs of consumers.

Portable Projectors:

Ultra-portable projectors (range from around 800-2000 lumens in brightness. Low or lights-off presentations are generally considered less desirable, as they allow for less visual interaction with the audience. A projector with at least 800 lumens is desirable for use in rooms where there will be little ambient light. You should also consider the size of your typical audience when selecting the right brightness. Larger audiences require larger images, which also require higher lumen output.

• 800 lumens for lights-off, low ambient light, presentations
• 1000 lumens with some ambient light - becoming the standard
• 2000 lumens with bright ambient light

Training/Conference Room Projectors

Typically, the brightest projectors (around 2500-7000 lumens) are slightly less portable. These larger projectors (around 13-30 lbs.) are perfect for conference rooms, training rooms and classrooms.

• 2500 lumens for audiences of less than a hundred with ambient light
• 3000 lumens for audiences of 100-200 with ambient light
• 5000 lumens for audiences of 100 or more under bright lights

Home Theatre Projectors

For home theater projectors, brightness typically ranges from 700 - 2000 lumens or more. Your viewing environment will be a big part of determining how bright your projector needs to be. Dedicated home theaters (rooms with controlled lighting and no ambient light) will not require as much brightness as a space with ambient light from windows or other household lighting. Projector People recommends the following lumen outputs:

• Dedicated home theaters need 700 lumens or better.
• Rooms with some ambient light should have at least 1000 lumens..
• Spaces with high ambient light need about 2500 lumens.

Tip:  In many cases, manufacturers rate projector lumen values based on data output, not video. Lumen output for video is typically not as high as data. For help determining which projector is right for your viewing environment, contact one of our professionals. Our projector experts have personally seen most units perform in video mode.

PORTABILITY

The portability of a projector is based on how easy it is to move around. There are three different sizes that projectors are based on.

MicroPortable (2-4 lbs.) projectors are primarely reserved for, but not limited, to the Road Warriors. These projectors are useful for anyone who has to travel frequently and does not want to bother with a cumbersome projector while rushing to their next location.

Portable projectors (4-9 bls. ) are a bit larger than microportable projectors but still allow you the ease and comfort of transportation. These projectors are ideal for those needing to move a projector from one room to another.

The third option is the installation (9 lbs. +) class of projectors. These projectors are reserved for larger venues or for those that know exactly where they want their projector and do not need to move it around.

SCREEN MOUNTING ORIENTATION:

Portable Screens -- Projector screens that travel from location to location readily.

Portable screens are designed to be carried from one place to another with ease. Road warrior presenters, traveling trainers, and entertainers on the go are a few typical users of portable screens. AV departments in schools, conference facilities, and hotels also benefit from portable screens because they add flexibility to their on-hand resources.

Manual Screens -- An economical choice for projector screens that stay in one location most of the time.

Manual screens are a popular choice because they are versatile, easy to use, and easy to install. They are also recognizable as the screens used in school classrooms. Manual pull-and-release systems allow you to lower the screen to the desired height and lock it into place. Manual wall and ceiling screens offer presenters a professional solution for virtually any situation. These screens can be rolled into a secure housing after use. Manual screens are considerably more affordable than the electric screens.

Electric Screens -- High-end projection screens that add elegance to their permanent location.

These are the crème de la crème of the screen universe. They're convenient and require less effort to open and close than manual screens. Available in ceiling-recessed, wall-mounted, ceiling hung (external), or ascending floor models, electric screens add a professional touch to a conference or board room and instant "wow" factor in a home theater setting. Electric screens are somewhat more complex to install than a manual or fixed screen, because they require a power source to operate.

Fixed Frame -- Permanently tensioned screen stretched around a frame and installed in a fixed location.

Fixed frame screens are tensioned screens that are designed for use in permanent locations. These screens integrate well into boardrooms, home theaters, and other frequent meeting spaces.

SCREEN SURFACES:

The way a screen surface refracts light is what differentiates one screen fabric from another. Manufacturers specify both gain and viewing angle to help you decide which surface is best for you. Take some time to think about the following questions before making your final decision:

Does your viewing area have controlled lighting or ambient light?

Does the room or rooms where you plan to use your screen have controlled lighting? Or is there ambient light from windows and office/household lighting? Your screen material can help minimize the effects of ambient light in rooms without controlled lighting. Screen materials can also help to increase the appearance of contrast or brightness of a projected image. See the descriptions on our surfaces page to learn more about surface characteristics.

What is the room configuration?

In rooms that are wider than they are deep, some audience members may find themselves at an angle to the screen where "fall-off" occurs, making it more difficult for them to see the image. In these situations, a screen surface with a larger viewing angle is preferred. Longer rooms may require larger screens so that those in the back of the room can see details more clearly.

What type of images do you intend to display?

The content you display on your screen will also play a part in determining which screen is best for you. Gray screen material is popular with home theater enthusiasts because the material adds the appearance of contrast to a video image. White or matte white screens are more popular in business applications. In situations where accurate color is desired, such as 35mm film display, a white or matte white surface will provide truer color representation.

ASPECT RATIOS:

Standard NTSC television, video, and computer display images in a 4:3 aspect ratio. High-definition television or HDTV is shown in widescreen (or 16:9) format. Most films shown in a cinema display in an even wider aspect ratio than that. Our most popular screen aspect ratios, as you might expect, are the 4:3 or 16:9 formats.

DA-LITE SCREEN SURFACES

Listed below are the different screen Qualities carried by Da-Lite. Don't forget to use the legend if you're curious about the key words.

SCREEN SIZE

Your screen size needs to fit your setting. A small screen won't work in an auditorium, and a large screen will overwhelm a small boardroom or home theater. You should also keep in mind the performance of your projector - what is the range of sizes the projector can display? Other factors to consider include the room configuration and the size of your typical audience.

Screen size recommendations from Da-Lite:

• Screen height should be approximately equal to 1/6 the distance from the screen to the last row of seats, allowing text to be read and detail to be seen in the projected image. Ideally, the first row of seats should be approximately two screen heights away.



• The bottom of the screen should be a minimum of 4 feet above the audience floor, allowing those seated toward the rear of the audience to see the screen. This may require additional screen "drop" for ceiling hung screens.

HDCP VS. DVI

What is DVI?

DVI, an acronym for Digital Visual Interface, is a technology developed in 1999 to enable digital-to-digital high bandwidth data transfer from a computer to a monitor.

What is HDCP?

As we mentioned earlier, DVI delivers exceptionally high quality video. In fact, the quality is nearly as good the original or master content. This previously unattainable quality has raised concern from Hollywood executives who fear video could be mass produced and illegally distributed, much like what has happened within the music industry. In an effort to protect this high definition home video content from being copied and illegally distributed, Hollywood studios employed tech companies Intel and Silicon Image to develop a method of security encryption. The standard they created is called High bandwidth Digital Content Protection or HDCP.

HDCP works by adding circuitry within the DVI connection on both transmitter (DVD player, cable box, etc.) and the receiver (projector, LCD TV, etc.) that encrypts video content. Software such as DVDs will not be affected as was the case with tapes for your VCR. Instead, the source players and the display device will be responsible for the encryption.

Why use DVI?

DVI is the fastest way to transfer data or video. It beats every other connectivity standard hands down. DVI is a 24-bit digital RGB interface that can support computer resolutions as high as 1600 x 1200 (UXGA), and the cinematic-apex, 1080 progressive high definition format. In fact, it is capable of supporting even higher bandwidth using a Dual Link. Dual link DVI connections can produce double UXGA bandwidth, but almost no one is using dual link today.

Using DVI with a digital display device, such as a projector or flat screen monitor, will create an entirely digital-to-digital connection. With a VGA cable the information from a digital source like a computer has to be converted from digital to analog . If you were using a projector there was an additional conversion back to digital. Each conversion slightly degrades the quality of the final image. Theoretically a DVI connection will therefore provide the least number of conversions, providing the consumer with the best quality image.

Why wouldn't I want to use DVI?

Although it is a high-bandwidth connection, DVI does have some limitations. If your home theater setup requires that you run cables longer than 6 feet from source to projector, DVI may not be the best choice for you. Signal degradation in DVI is like most digital devices in that content becomes unwatchable, suffering from "sparkles" or "blue-screening" if the cable has been run too far. Signal amplifiers are available that allow for longer cable runs, but they are not cheap. A solution built in to the cable or display device is likely on the way, but is not here yet.

Because DVI is a new technology, still in version 1.0, it is not yet entirely standardized. There are some compatibility issues with chip designs, board sets, and in the interconnecting of the cable assembly. With most compatibility problems the issue is periodic video artifacts rather than complete failure.

Can I watch HDTV without a DVI connection on my projector?

Yes. Using a component video (YPbPr analog) input you can still watch HDTV content. If the video source (DVD player or cable box) is able, you can watch video as high as 1080i with this type of connection. The primary difference between the two types of connections is that component video will be a converted analog signal rather than a pure digital signal.

A high-definition analog signal still looks immensely better than a regular analog broadcast signal. Particularly when viewed on a large screen. In some cases, an analog image will often look as good (and sometimes better) than a digital signal.

Can I watch HDTV content using DVI without HDCP compatibility?

Yes, if the cable box or DVD player is capable of outputting HD quality signals and is not using the HDCP encryption yet, you will still be able to use your DVI connection to watch high-definition content. Remember you can also watch analog high-definition content via a component video connection.

Will projectors with DVI and without HDCP be made backwards compatible?

It isn't clear whether a legitimate, legal solution will be developed for those consumers who purchased DVI products before the advent of HDCP. Projectors without HDCP compatibility will not be made compatible with a simple firmware update. There is hardware required to make the conversion. However, there may be a solution using an IEEE 1394 converter that allows for digital-to-digital HDTV from legacy DVI devices.

What about DTCP and IEEE 1394 FireWire?

Digital Transmission Content Protection, or DTCP , is the encryption standard used to protect content which is sent over the IEEE 1394 of FireWire standard. The DTCP standard allows for use of a set top box which decodes the digital signal. DTCP is unlike HDCP which requires a direct link between source and display device, however, due to the bandwidth limitations of FireWire, it can output no higher than a 480p digital signal.

FireWire is not a common connection on video projectors, but is more commonly found on plasma and LCD TV digital displays.

New on the Horizon -- HDMI.

High Definition Multimedia Interface is a descendant of DVI. Like DVI, it is a digital cable and connection that supports digital data transmission. Unlike DVI which supports only video transmission, HDMI supports both high definition video and audio. HDMI will offer 'legacy' support of older DVI connections.

DirecTV, EchoStar (Dish Network), and CableLabs are supporting the new HDMI standard.

INTERLACED (3:2 PULLDOWN) VS. PROGRESSIVE SCAN:

Standard 480-line NTSC TV broadcasts (incl. cable television), VCR, DVD and laserdisc signals are sent in an " Interlaced Scan" format. A TV screen first draws the image's odd lines, one at a time sequentially from top to bottom (which takes 1/60 of a second), and then fills in the even lines (taking another 1/60 of a second). That is, the full picture (top to bottom) is first drawn with half its information hollowed out, and then the other half is filled in -- the entire process taking 1/30 of a second.

A newer and superior scanning method called "Progressive" permits the entire picture to be drawn sequentially from top to bottom without the odd/even interlacing. Some newer DVD players now have outputs for both an interlaced and progressive scan image. And HDTV signals are now being broadcast in both progressive and interlaced formats: 720p (720 lines of resolution in progressive scan format) and 1080i (interlaced).

Why reverse 3:2 pulldown?

Reverse the process? Am I kidding? Sadly no. There are a few DVDs available that come as progressive scan rather than interlaced, but not many. When you consider the fact that the majority of people are watching DVDs on NTSC televisions and do not have the luxury of seeing them on the big screen from a front projector, it makes sense. It's okay to think about how much better our world would be if we all had giant progressive scan images from projectors in our homes, but it doesn't solve our problem. What does solve the problem is reverse 3:2 pulldown or de-interlacing.

"Reverse 3:2 pulldown" is the process of finding the original film frame. It would be easier to find the original frame if the new frames were not interlaced. However, as we mentioned before, we created extra video frames, which are interlaced, by combining two different non-interlaced film frames. Simply displaying each video frame in progressive scan will create 'jaggies' and other distortion.

Luckily, new progressive scan DVD players come with the de-interlacing built-in. Basically, the DVD player uses an MPEG decoder that knows which frames will create images with the least distortion and puts them together for you. Some DVD players will do this better than others, so you will need to do some homework if you are a stickler. For most of us, the picture is so much better than NTSC a few glitches won't matter.

Some people may think that a simple line-doubler will solve this problem. But without reversing the 3:2 pull down process, a projector with an internal line-doubler will try and 'double' or de-interlace frames that are inconsistent. What you will see is a periodic jumbled mess of confused images with artifacts, and artifacts do not make for film-like images.

So in your quest for the best image for your money, what is the easy answer? Get yourself a progressive scan DVD player with 3:2 pulldown detection and use your projector's component input. You could spend the money on a projector with the reverse 3:2 pulldown as well, but getting it in the DVD player will cost you less, and it is a little more efficient because the conversion process is taking place at the source. Using your component input will bypass the internal circuitry of your projector and show the progressive, film-like image in all its native glory.

DIGITAL VS. ANALOG:

Digital Visual Interface connections allow users to create a digital-to-digital connection between their display and source. We most commonly see the digital-to-digital connection between flat screen monitors and computers. However, new HDTV set top boxes can be found which offer DVI output.

The signal your television receives with an antenna is analog. Sometimes the picture is fuzzy, sometimes it comes in perfectly clear, and sometimes it fades in and out. With a digital signal, the signal is either on or off, so "fuzziness" is not possible. That is not to say that an analog signal always looks fuzzy. A high quality analog signal also produces beautiful, clear images. The signals are just not quite as consistent as digital.

LINE DOUBLES AND SCALERS  

Unlike TV picture tubes and computer monitors, projectors don't actually "draw" the picture. Rather, at any given split-second in time they are either projecting image or not (i.e., the pixels are either "on" or "off"). Thus, an attempt to project an "interlaced" signal would result in every other line (the "odd" lines) being projected by themselves for 1/60 of a second, followed by just the even lines, resulting in a picture worse than any big screen TV.

To accommodate incoming interlaced signals such as from a TV broadcast (incl. cable), VCR, DVD or laserdisc, most projectors contain deinterlacer or "Line Doubler" circuitry that changes the interlaced signal into a progressive EDTV format. This is accomplished by waiting a full 1/30 of a second to receive both the odd and even lines before projecting them together onto the screen. During this split-second wait, the previous image frame continues to be projected a second time, so there is a fully formed image being displayed at all times.

Despite its name, there is not actually a "doubling" in the number of lines of resolution. But there is a doubling of the amount of time that each image frame is displayed, resulting in a picture that not only is devoid of "flicker," but which is also brighter.

With a high-quality line-doubler (and not all of them are), the resulting picture quality from an "interlaced" source is absolutely superb.

Wireless vs. Standard

Projectors have made impressive technological advances in recent months. They can now be added to existing networks they can produce HDTV-quality video, and they are lighter, brighter, and less expensive than the projectors of a year ago. What more could you want? Wireless connectivity, you say? You got it!

Manufacturers like NEC, InFocus, Sharp, Toshiba and more have wireless projectors that are available now. Using 802.11b (11 megabits per second) protocol, projectors and computers with compatible wireless cards can communicate without wires.

What can wireless projectors do today?

• Toggle between multiple computer sources with one click.
• Allow users to present from a computer placed anywhere in a room.
• Run PowerPoint presentations (with limited animation).
• Show edits to a document, such as an Excel spreadsheet, in real-time.

The future of wireless projectors.

Wireless full-motion video transmission is currently not possible with wireless projectors because the 802.11b does not provide the bandwidth. However, in the very near future, using the transfer specification 802.11a or 802.11g (54 megabits per second), wireless video will be possible. This increased level of performance is great news for projector users at home and in the office. At home, new digital cable set-top boxes and gateways, cable modems, satellite receivers, PCs and PDAs are all potential applications for new streaming video technology. HDTV signals can also be supported by the new protocol. In the office, wireless projectors will be able to support multimedia and slide transitions making for more dynamic presentations.

Want a wireless projector now?

If you are not concerned about projecting wireless video, there are many solutions available today that will fit your wireless needs. OTC Wireless makes a plug-and-play WiJet wireless adapter that can make any display wireless. There are also many projectors that have wireless functionality built-in. Some manufacturers, like InFocus and Proxima, offer a modular solution that will allow for upgrades to higher bandwidth standards. The InFocus LiteShow is an upgradeable and entirely cable free solution that works with many current and older models.

DIGITAL LIGHT PROCESSING (DLP) :

DLP™ (single chip) - Digital Light Processing

The single-chip DLP™ is the most portable of all our players. Currently you can find single-chip DLP™ projectors that weigh less than 2 pounds. Digital Light Processing is the product of the great minds at Texas Instruments. DLP™ uses a single Digital Mirror Device (DMD) chip that has thousands of tiny mirrors, each representing a single pixel. These mirrors tilt back and forth and deflect light as indicated by the source to create the image. One limitation so far has been brightness. Currently the brightest single-chip DLP™ on the market is just 2500 lumens compared to the 5,000+ lumens of LCD and three-chip DLP™ projectors. Becuase of their deep, rich blacks and high contrast ratios. DLP™ projectors have been a popular choice among home theater enthusiasts.

DLP™ (three-chip) - Digital Light Processing

The three-chip DLP™ has the best looking images of all the players. The three-chip system is much like the single-chip DLP™ only better. The image quality of the three-chip DLP™ is unsurpassed. Unfortunately it is also the most expensive. Today's three-chip™ DLP projectors cost anywhere from $15,000-$30,000 or higher. Unlike CRTs and single-chip DLP™ projectors, three-chip DLP™ can have very high lumen output levels.

LIQUID CRYSTAL DISPLAY (LCD):

LCD projection technology is the current leader of the pack, having captured the majority of the market share of all projectors sold. Most LCD projectors have three panels. Each panel is a prism that allows blue, red, or green light through its pixels. These separate colors are then converged and projected. Electrical signals turn on pixels within a set based on the resolution of the unit. LCDs are known to produce greater color definition, offering more shades or variations of color than single-chip DLP™ projectors. DLP™ projectors can sometimes burn definition out of the highlights and shadows with their vibrant colors. Newer LCD projectors include special optics enhancers like micro-lens array that minimize pixelization known as the "screen door effect." New LCD projectors have contrast ratios as high as 800:1. By comparison, DLP™ projectors contrast ratios are as high as 3000:1. The portability and brightness of LCD projectors have made them a popular choice for traveling presenters. The lightest LCD projectors weigh-in at about 4 lbs.

HDTV STANDARDS