Want to learn about 3D TV? Take a look at our 3D TV buying guide.
LCD vs plasma vs LED
Plasma TVs use a sheet of miniscule individual plasma cells that create a picture when an electrical charge is applied — examples of plasma televisions include the Panasonic TH-50VX100W, LG 50PS80ED and Panasonic TH-P50G10A.
LCD televisions, on the other hand, use liquid crystal compressed between two glass plates; an image is created when electricity is applied to these crystals. LCD televisions can range from cheap models like the Changhong LT4268TA to more expensive sets like the Sony Bravia KDL40W5500 and the Toshiba Regza 42RV600A.
LED TVs use liquid crystal, but unlike regular LCD televisions they use a backlight made of hundreds of LEDs (light-emitting diodes) instead of a fluorescent lamp. The LEDs can be evenly distributed around the back of the television’s panel or situated in the edges of the screen to create a very thin display chassis. LED televisions include the Sharp LC40LB700X, Samsung Series 7 (UA46B7100) and Sony Bravia KDL55XBR45.
How well an image is displayed on a television panel — whether it is a Blu-ray movie, a HDTV broadcast or a high-definition video game — depends on a television's display technology and its image processing capabilities.
A television's contrast ratio represents its ability to show detail in high contrast areas of the screen, in the form of minute gradations of colour and blacks or whites. For example, a panel with a low contrast ratio will struggle to show the higher or lower extremes of an image. In layman's terms, this means detail will be lost in bright areas as well as in dark scenes. In a Blu-ray movie, for example Batman Begins, the loss of detail in dark scenes will quickly become apparent.
Most manufacturers increase the contrast capabilities of their screens by dynamically altering backlight brightness. This allows extra detail to be shown in dark scenes and can be a life-saver for a panel with a low static contrast ratio. Some manufacturers have taken their estimations of this dynamic contrast ratio to excess, rating their screens at contrast ratios of 1,000,000:1 — and even higher. While these figures demonstrate the advantages of dynamic contrast ratio alteration, they don't need to be a big factor in your buying decision.
It is generally accepted that plasma televisions have better contrast ratios than LCD panels, due to the fact that a plasma television can completely deactivate the light source for individual segments of the screen. This means sections of the screen can be completely dark while others are displaying bright colour, unlike a traditional LCD screen which has a single backlight array that can only alter brightness levels for the entire screen.
The latest LED backlight technology allows the television to individually control backlight segments. This technology allows for contrast ratios similar to those produced by plasma television panels. However, edge-lit LED televisions — usually available in an ultra-slim form factor — will have lower dynamic contrast ratios than the backlit LED models so be sure to check this detail before you purchase.
The narrower a television's quoted viewing angle is, the smaller the range in which it produces a 'perfect' image with no loss of contrast or colour. Many manufacturers quote an unrealistically high viewing angle — close to a full 180 degrees in some instances — but the best way to test this is to test the screens in person.