AVPartner Glossary: From A to Z in A/V!

AVP Glossary

The World of A/V and projectors can be difficult to understand, and we always want you to have a clear understanding of the technology and features associated with the projector or audio-visual product that you are researching. That way, you'll be able to determine exactly what you need, and we can better help find it for you.

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

• Analog
An analog video signal uses a variable voltage to equal the pixel value, as opposed to digital pulses. A digital signal will usually produce better video.

• ANSI
ANSI stands for the American National Standards Institute. The brightness on a projector is always preceded by ANSI because they've officially approved this format of lighting. You may hear someone in the A/V industry say, "The projector has 2000 ANSI's." That is simply a quicker way to say, "2000 ANSI lumens".

• ANSI lumens
ANSI lumens refers to the degree of brightness illuminated in a projector's display, measured in "candles". A projector with 2000 ANSI lumens is twice as bright as one that has 1000 ANSI lumens.

• Aspect ratio
The aspect ratio of a projector is the ratio of width to height of a projected picture. The two main aspect ratios today are 4:3 and 16:9. A projector that projects a 4:3 aspect ratio is the same ratio as your television or computer monitor, where the width is slightly more than the height. A projector with 16:9 aspect ratio is also called "wide-screen format". This aspect ratio resembles that of a movie theater screen.

• Auto balance
Auto balance is a system that detects errors in color balance in black and white areas of the picture, and automatically adjusts the black and white levels of both the red and blue signals as needed for correction.

• Built-in loop through
A built-in loop through in a projector allows another screen or projector to be connected, displaying the same signal. Educators tend to need projectors that have a built-in loop through.

• Chrominance
The chrominance of a picture refers to its color saturation and hue.

• Color temperature
Color temperature refers to the amount of "whiteness" in a light source. Metal halide lamps have much higher color temperatures than halogen lights and bulbs.

• Component video
Component video delivers the best quality video image possible. Component cables divide the image from the system into three separate colors for the best possible picture, where as composite cables are the yellow (video) and red, white (audio) connections that come standard with game systems these days. Component video improves the picture quality by not only separating the color from the black-and-white portions of the picture but by further splitting the color information into two color-difference signals.

• Composite video
Composite video is the standard RCA jack for video, which includes a familiar yellow plug providing an analog video signal. Composite video is one of the most common A/V connections, however it is certainly not the best since it has a combined picture signal, including vertical and horizontal blanking and synchronizing signals.

• Compression
Compression is used to convert one resolution to another. For example, a projector that has SVGA resolution may accept XGA resolution and compress it to SVGA, resulting in a clearer picture.

• Contrast ratio
The contrast ratio refers to the ratio of darkness to brightness. Many LCD projectors have a contrast ratio of 400:1. This means that the lumen output of a projected white image is 400 times greater than that of a projected black image.

• Dichroic
Dichroic is a mirror or lens in a projector that reflects or refracts wavelengths of light, thus separating the white light into red, green and blue.

• Digital signal
A digital signal is strung together in infinite variations at rapid speeds to transmit computer information. Most projectors utilize analog signals today whether it be from component, composite or RGB cables.

• Distribution amplifier
A distribution amplifier allows one source signal to be amplified and distributed over significant distances, through multiple outputs.

• DLP (digital light processing)
DLP is the display technology developed by Texas Instruments that uses mirrors to display an image. Advantages to DLP technology in projectors are the ability to produce amazingly high contrast ratios and super light projectors. The disadvantages of DLP are generally colors that are not as vibrant and saturated and what's called a "Rainbow Effect". A rainbow effect is an illusion of artifacts that some people will see when watching video on a DLP projector.

• DVI (digital visual interface)
DVI refers to the digital interface between projectors and PCs. A projector that has DVI can send a digital-to-digital connection, without converting to analog, thereby delivering a clearer image. The general rule with DVI cables is that 5m (16ft) is the maximum length for trouble-free operation.

• Eco-Mode Technology
High-efficiency feature that doubles lamp life while providing quieter operation. This smart innovation saves money and eliminates the hassle of frequent lamp replacement.

• Focus
The focus on a projector defines the minimum and maximum projection distances. Most projectors today have an Auto Focus button that will automatically focus the image. You can still adjust the image using the manual focus.

• Horizontal / Vertical Lens Shift
A projector feature which allows for precise image positioning for speedy installation and usage.

• Interface
Interface refers to the connection between different elements of a system, which converts the signal so it can be recognized by both elements.

• Keystoning
Automatic keystoning is a projector feature that creates a uniform image top to bottom by correcting the image if it's projected onto the screen at an angle. Today several projectors will keystone correct up and down and side to side.

• LCD (liquid crystal display)
LCD technology uses three glass panels inside the projector separating the color spectrum into red, green, and blue. The light passes through these panels and creates the image on the screen. Most projectors are either LCD projectors or DLP (digital light processing) projectors. Advantages to LCD are better color saturation and sharper video imagery that uses a greater light efficiency. There is less loss of light and richer quality of the image that results in beautiful video.

• Lumen
A lumen is a measurement of light. The higher the lumen count, the brighter the projection.

• Luminance
Luminance refers to the color intensity of an image.

• NTSC
NTSC, or the National Television Standards Committee, is the video transmission system used in America .

• Pixel
A pixel is a small dot that represents a single element of a display. The more pixels that make up an image, the clearer and more detailed that image will appear.

• Polysilicon
Polysilicon is a material used in the manufacturing of the LCD screen. It gives a better contrast ratio and faster response time than the TFT LCD screens.

• Rainbow effect
On DLP projectors, the rainbow effect is created by the inability of the DLP color wheels to refresh pixels fast enough, resulting in some color separation on the edges of fast-moving objects. This results in an appearance of artifacts on the screen when watching video. Some people are more prone than others to seeing the rainbow effect.

• Resolution
Resolution is defined as the number of dots, or pixels that a display uses to create an image. For example SVGA resolution is 800 x 600 pixels (800 pixels across the width of the screen by 600 pixels down the height of the screen) and XGA resolution is 1024 x 768 pixels. The higher the resolution, the sharper the image.

• Scan converter
A scan converter in a projector converts a digital signal from a computer to a video signal, thus allowing it to be shown on a video projector or TV monitor.

• Screen Gain
Screen gain describes the extent to which a projection screen can make a projected image appear brighter. For example, a screen gain of 1.3 will make a projected image look 30 percent brighter than it would if the same image were projected on a screen with a gain of 1.0, or neutral.

• Short throw lens
A short throw lens is designed to project the largest possible image from a short distance. Most projectors are equipped with an average throw lens, however there are a few projectors on the market that come with a short throw lens.

• SVGA Resolution
An SVGA resolution projector is one that projects images that are 800 pixels wide by 600 pixels high. Today, this is the lowest resolution projector that you can buy. SVGA resolution projectors are best for displaying PowerPoint type presentations with large images and fonts.

• Throw distance
The throw distance is the distance from the center of a projector lens to the center of the screen onto which it's projecting. The longer you need to throw the projected image, the brighter your projector should be.

• UXGA Resolution
A UXGA resolution projector is one that projects images that are 1600 pixels wide by 1200 pixels high. There are only a few select applications where a projector with UXGA resolution is needed. These specialized applications might include surgical and medical needs and the military. There are only a handful of projectors with UXGA resolution, and they aren't cheap!

• Ventilation
Airflow through a projector's internal components for the purpose of cooling the lamp, or light source. A projector's ventilation is usually found on the rear or side. It's important not to block the projector's ventilation because it may shorten the lamp life and damage the projector.

• XGA Resolution
An XGA resolution projector is one that projects images that are 1024 pixels wide by 768 pixels high. A projector with XGA will produce better images and video over an SVGA resolution projector. An XGA resolution projector will display more detailed images.

• Zoom lens
A zoom lens is a feature on higher-end projectors that allows adjustment of focal length. A zoom lens can either be digital or manual.