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Aspect Ratio

The Aspect Ratio of a display is the simple comparison of width to height as a ratio, not a measurement. 16:9 is the optimal ratio for un-interactive viewing because it best fits the area the eyes can see and allows them to take in the most information without straying further from the centre of the screen. A 16:10 ratio is preferred for widescreen displays that are primarily aimed at computer monitor use, as computers are used in a different way to televisions, with features such as horizontal task bars, application interfaces, and heads up displays being seated mainly along the top and bottom, tucked away from the central viewing area, and documents and web pages being designed to scroll down, rather than across.

Brightness

Brightness on display units is measured in candelas per square metre or cd/m2 (1 cd/m2 is sometimes called a nit). This is not much use on its own, as a high brightness display with low contrast ratio would not have a good output of black. Likewise, a high contrast ratio with low brightness would have an extremely dark black output, and be best suited for darker rooms. Both brightness and contrast ratio need to be taken into consideration to get the full picture.

Comb Filter

A Comb Filter is a device that separates chrominance from luminance to improve picture resolution, to minimize picture distortion and to reduce distortionary colour artefacts, such as dot crawl and shimmering.

Component video

Component video elements that make up a video signal: luminance, which represents brightness in the image, and separate red and blue signals (expressed as either Y R-Y B-Y or Y Pb Pr). Component video signals are superior to composite and S-video images because of improved colour purity, superior colour detail, and a reduction in colour noise and NTSC artefacts.

Composite video

 Composite video is the video signal combining luminance and chrominance, the burst signal and sync data (horizontal and vertical). A direct video connection using an RCA-type plug and jack; its signal quality is better than the RF type of connection but inferior to S-video and component video.

Contrast Ratio

The Contrast Ratio is how many times brighter the brightest possible output of the screen is, compared to the darkest possible output. A 400:1 contrast ratio would mean that the brightest white is 400 times brighter than the darkest black. Even a presence of relatively dim light in a room will render devices with infinite contrast ratios virtually indistinguishable from those with poor ratios, while in a dark room, the human eye cannot notice levels greater than about 800:1. A typical Movie Theatre screen will have about 500:1 contrast ratio.

Here is an example of how to think of contrast, for a TV with 800cd/m2 brightness and 3000:1 contrast ratio. The brightest possible white will be 800cd/m2 in brightness, and the darkest possible black will be a 3000th of that, or 800/3,000 = 0.2cd/m2

DVI

The Digital Visual Interface (DVI) is a video interface standard designed to maximize the visual quality of digital display devices. DVI is the best way to connect to a computer, for using the TV as a large monitor.

HD Ready

A Display device that is HD Ready means that it meets a set of requirements needed to show protected High Definition content.

These requirements are:

• The minimum native resolution of the display is at least 720 pixels high in a wide aspect ratio.
• DVI or HDMI inputs accept 720p and 1080i HD video formats.
• The DVI or HDMI input supports copy protection (HDCP).

HD Compatible

This term is given to displays that can accept HDCP protected content through HDMI or DVI inputs, but don’t meet the resolution requirements and have to down-scale the picture to display it.

HDMI

The High-Definition Multimedia Interface (HDMI) is an industry-supported, uncompressed, all-digital audio/video interface. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, a DVD player, or an A/V receiver and a compatible digital audio and/or video monitor, such as a Digital TV.

LCD TV

LCD stands for Liquid Crystal Display, and is a screen technology comparable to Plasma. LCD TVs have a longer life span and use less power than Plasma and CRTs, and can double as Computer Monitors with their ability to display very sharp images. Like Plasma TVs, LCDs are also very thin, and recent improvements have given them better viewing angles at up to 170 degrees, making them perfect for family viewing and playing games. With the introduction of HD Ready models, the future of home entertainment is brighter than ever before.

Lines of resolution

A method of comparing the relative amount of detail in a television picture, usually measured by counting the number of horizontal lines that can be reproduced from top to bottom of the television screen. It is not the same as scanning lines that form a picture. DVD incorporates 480 lines of resolution In (SDTV) analogue television, with 525 scanning lines, lines of resolution vary: VHS has 240 lines and SVHS has 400 lines. Analogue broadcast television use 330 lines of resolution.

Picture in Picture (PIP)

Picture in Picture (PIP) allows you to watch more than one TV channel or input at the same time. 2 Tuner PIP TVs use two independent TV tuners to supply the different TV pictures, or they can display a combination of any other inputs. 1 Tuner PIP TVs require the use of an 'external tuner' to provide a second TV signal, or they can display a combination of other inputs.

Pixel Resolution

The number of pixels horizontally (Lines of Resolution) by the number of pixels vertically, this is how many independent dots of colour the screen can display. In a few circumstances, the number of pixels may appear to not match the aspect ratio of the display, such as 1024x768 pixels (4:3 ratio) on a 16:9 screen. This is not a misprint, but simply means that each pixel is not square, but slightly rectangular. In Plasma technology, this can actually mean that colours are displayed more accurately, depending on the design and manufacturing process, although the level of detail would be lower than it would be if there were more pixels.

Plasma TV

Plasma TVs are very large and thin, with high contrast ratios, smooth images and superb colour reproduction. The difference between conventional CRT Televisions and Modern Plasma Screens is huge, and with a HD Ready Display, you can watch films in Movie Theatre quality. You can also view television broadcasts in High Definition, and Next Generation Gaming in glorious colour

Response Time

Pixel Response Times apply to LCD Televisions only, as Plasma Displays use a different type of technology. The pixel response time in milliseconds is the time it takes for a pixel to go from black to white and then back to black. In the earlier days of LCD display technology, higher response times meant that in fast moving scenes, the panel would not be able to draw each rapidly changing frame in time, and a slightly blurred, ghosting effect could be seen in some places. This is no longer a problem for LCD screens, as response times of 12ms or less appear perfect to the human eye, while up to 25ms will provide very little, if any, image distortion.

S-Video

Higher quality video input and output than composite video connection that segregates chrominance and luminance signals for optimum reproduction from high-quality video sources such as SVHS, Hi8 and DVD players. Not as good as component video, but more common