HDTVs are here

TECHNO BEAT

In-Stat predicts that over 60 million households will have at least one wide screen, high-definition TV (HDTV) display in their home by end 2007. As broadcasters convert to digital content, HDTVs could provide an altogther different viewing experience.

But what is a HDTV? Not all big screen qualify to be HDTVs. Unlike standard-definition TVs, HDTVs sport high display resolutions and wide aspect ratios or rectangular displays. Imagine 720 or 1080 lines of resolution compared to the 340 to 480 lines we are used to in India. It also comes with a wider 16:9 aspect ratio (as compared to the current 4:3). This enables wider screens and a better viewing experience.

The formats used in HDTV are 720p "� 1280x720 pixels (p stands for progressive); 1080i "� 1920x1080 pixels (I stands for interlaced); and 1080p "� 1920x1080 pixels. "Interlaced" or "progressive" refers to the scanning system.

In an interlaced format, the screen shows every odd line during the first scan, and follows that up with the even lines in a second scan. Since there are 30 frames shown per second, the screen shows one half of the frame every 60th of a second. For smaller screens, this is passable.

As screens get larger, the flicker is noticeable. Progressive scanning shows the whole picture, every line in one showing, every 60th of a second. This provides for a much smoother picture, but uses slightly more bandwidth.

LCD, Plasma, DLPs or LCoS? LCD (Liquid Crystal Display) screens are common (your PC, camera, etc.) because are thinner and lighter and draw much less power than cathode ray tubes (CRTs "� used in your analogue TV) and Plasma Tvs. Plasma TVs often have larger screen sizes, faster response times and wider viewing angles than LCD TVs.

However, Plasmas can dim over time. LCD TVs are usually better for viewing in a lighted room. However, they generally do not match the size of plasma screens. LCD displays, though, will have a higher resolution if compared to similar-sized plasma screens.

A 50-inch plasma TV will have a resolution of 1366x768 (true HDTV experience starts with this resolution), while a 45-inch LCD displays 1920x1080 (1080p) resolution. Those extra pixels and the production process of LCDs cost more money to produce.

Digital light processing (DLP) and liquid crystal on silicon (LCoS) are both microdisplay rear-projection TV technologies. DLP is a Texas Instruments-trademarked technology in which light is projected onto a series of tiny moving mirrors, with each mirror representing 1 pixel.

LCoS is similar, but light is projected onto liquid crystal-coated silicon chips instead of mirrors. Both technologies offer very clear resolutions, but since they use rear projection, they are often bulkier than flat panels.

Incidentally, a projector using DLP, LCoS or LCD technology can hang from the ceiling or sit on a table to throw up a picture on a separate screen.

The problem with HDTV in India is not so much with the TV sets as with the broadcasters. They will have to squeeze the increased picture detail and higher quality surround sound into the same bandwidth used by analogue television.

Compression software (MPEG-2/4), very similar to what is used in personal computing, makes this possible. We are seeing a lot of convergence happening. While it's true that most of our networks are still analogue, there's direct-to-home (DTH) and Internet Protocol TV (IPTV) making rapid inroads in the broadcasting markets.

Digital networks should become a reality in the near future, and with it will come high-definition content. You are sure to experience the full power of your HDTV. Till then, you can watch DVDs and get a bigger and better quality picture.