HD TV Guide
High-definition (HDTV) is possibly the biggest thing to happen to TV since the advent of colour. Why is it such a powerful development? In a nutshell, HDTV is not like any TV you will have experienced before. Get ready for the most life-like images you have ever seen on the small screen, with colour and clarity that is unrivalled. To display HD pictures HDTVs must be supplied with a signal from an HD source such as a Blu ray or HD DVD player or Sky HD. See our Blu ray hardware and HD DVD hardware sections for HD disc players.
High-definition television potentially offers a much better picture quality than standard television. HD's greater clarity means the picture on screen can be less blurred and less fuzzy. HD also brings other benefits such as smoother motion, richer and more natural colours. The colours will generally look more realistic, due to the greater bandwidth. With HDTV the lack of imperfections in the television screen often seen on traditional television is another reason why many prefer high definition to analogue. Problems such as snow caused from a weak signal, double images from ghosting or multi-path and picture sparkles from impulse noise are a thing of the past. These problems often seen on a conventional television broadcast just do not occur on HDTV.
HD programming and films will be presented in 16:9 widescreen format (although films created in even wider ratios will still display "letterbox" bars on the top and bottom of even 16:9 sets ). Older films and programming that retain their 4:3 ratio display will be presented in a version of letterbox commonly called "pillar box," displaying bars on the right and left of 16:9 sets. While this is an advantage when it comes to playing 16:9 movies, it creates the same disadvantage when playing 4:3 television shows that standard televisions have playing 16:9 movies. A way to address this is to zoom the 4:3 image to fill the screen.
The Technical Bit
HD ready concerns the ability of televisions to display high-definition pictures. However, the fact that a product bears the label "HD ready" does not necessarily mean that it can display the full picture resolution possible from a HD source. Most HD-ready sets do not have enough pixels to give true pixel-for-pixel representation without interpolation of the higher HD resolution (1920x1080). To be awarded the "HD-Ready" certification a display must be capable of displaying a picture with a minimum native resolution of 720 physical lines in wide aspect ratio from an HD input via analogue YPbPr, and DVI or HDMI. The HD capable inputs must accept the following HD video formats; 1280x720 @ 50 and 60Hz progressive ("720p"), and 1920x1080 @ 50 and 60Hz interlaced ("1080i"). The DVI or HDMI input must support content protection (HDCP).
"HD ready" display devices support analogue YPbPr as an HD input format to allow full compatibility with Today's HD video sources in the market. Support of the YPbPr signal should be through common industry standard connectors directly on the "HD ready" display device or through an adaptor easily accessible to the consumer. The term HD compatible is also being used in Europe to indicate that a display device has HDMI capability but with lower than HD-ready resolution.
The "i" in these numbers stands for "interlaced" while the "p" stands for "progressive". With interlaced scan, the 1,080 lines are split into two, the first 540 being displayed on one frame, followed by the second 540 lines displayed on another frame. This method reduces the bandwidth and raises the frame rate to 50-60 per second. A progressive scan displays all 1,080 lines at the same time at 60 frames per second, using more bandwidth.
Many of the more recent HD Ready flat screens feature a resolution of 1,366x768 pixels. This will display the commonly used 720p and 1080i formats, although 1080i/1080p signals will be downscaled to fit. To display 1080i/1080p signals in their entirety, you'll need a screen with a resolution of 1,920x1,080 pixels and a HD source. Screens capable of displaying the full 1920x1080 resolution progressively have been dubbed "Full HD". This is the ultimate high-definition standard, the most detailed picture, displayed progressively. See our HD TV pages for Hd Ready and full HD TV sets.
