Demystifying the World of HDTV

Demystifying the World of HDTV

Now that the price of high definition televisions (HDTVs) has come down to an affordable level, the task of figuring out which system meets your needs still remains daunting. Back in the days of tube TVs, choosing a new set was purely based on size - the bigger the screen, the better the picture - and if you stuck to the major brands you ended up with a decent choice. Today, wading through the sea of technical jargon to figure out the different television technologies is as confusing as trying to figure out organic chemistry. What's 720p and 1080i? What's contrast ratio? Plasma or LCD? With this flood of information, it's enough to make your head swim. This article will attempt to clear the murky HDTV waters.?

The Elements of HDTV

When you go shopping for a HDTV at your local electronics superstore, you are bombarded with a host of technical jargon. Let's break down the typical "features" they list to better understand what they mean.


The most used and often most confusing terms are 720p and 1080i -- two different HD standards. These terms can be broken up into two parts. The number refers to the number of vertical lines the screen can display from the top of an image to the bottom. To qualify as a "HDTV", a television must have a minimum of 720 vertical lines (a standard television only has 480 lines) with a 16:9 aspect ratio(more on this later).

The second part - the letter -- denotes how the picture is displayed: interlaced (i) or progressive scan (p). In interlaced scanning, the image is displayed in two fields. One field consists of all the odd numbered lines and the other displays the even lines. The television scans at 60 fields per second with each field alternating to form the full image. On the other hand, progressive scan does not split the image, displaying the every line of the image in one frame. This creates a more detailed image than interlaced scanning.

So how do they compare? While 1080i displays more lines than 720p, the advantages of progressive scan over interlaced scan -- doubling the amount of times the TV displays the image per second -- makes the two formats virtually indistinguishable from one another.

Many new HDTV sets now support 1080p that leverages more lines (1080) and progressive scanning (p) to boast the best image quality of all HDTVs.

Aspect ratio

As stated earlier, a television must have a 16:9 aspect ratio to carry the proud name of "HDTV". Aspect ratio simply is the ratio of the width of the screen to its height. The televisions we all grew up with sported 4:3 ratios. By definition, a widescreen television must have a16:9 aspect ratio meaning a 16 units wide by 9 units high rectangular picture.

Contrast ratio

Another advertised "feature" of a HDTV set is the contrast ratio. The contrast ratio basically measures the difference between the brightest white and the darkest black on the screen. A higher contrast ratio allows the television to represent colors as they should be causing the image to seem more realistic and vibrant - jumping out of the screen. As with most things in life, the higher the better when it comes to contrast ratio, thus a 3000:1 contrast ratio is better than 500:1.??

Many Flavors of HDTV

When you walk into your local electronics store, the only differences you see between the myriad of televisions on display is the size. However, upon closer inspection, you find that HDTVs are separated into two groups: flat-panel and projection. Lightweight and wall mountable, flat-panel TVs use either plasma or LCD technology to stay sexy and sleek ruling as the supermodels of the HDTV world. Projection televisions are the slightly heavier and clunky cousins of flat-panel televisions. Though not mountable nor nearly as sleek, these systems provide good bang for the buck - if you have the real estate in your home.

Flat-Panel: Plasma and LCD TVs

Plasma uses electrodes to ionize gas sandwiched between two glass panels to create the TV image. LCD (Liquid Crystal Display) uses a light source that sits behind a mesh of liquid crystals between two glass panels with an electric current activating the liquid in the crystals blocking the light -- acting as a shutter -- to create the TV image.

Because of how the two differing technologies work, plasma TVs typically have a better contrast ratio than LCD TVs, while LCDs consume less power and has a higher native resolution than similar-sized Plasmas.

Projection TVs: DLP and LCD

Developed by Texas Instruments, DLP (Digital Light Processing) technology uses an array of mirrors to create the TV image. A LCD projection television uses a single light source to pass through three LCD panels to create the image.

There is no clear-cut winner between these two competitors.? A slight edge goes to DLP TVs possessing better contrast ratio over LCD projection TVs.

The Ins and Outs of HDTV

Finally, make sure that you get the right video inputs for your HDTV. High-definition video can be piped to your high-def TV set via component, HDMI (High-definition Multimedia Interface) or DVI (Digital Visual Interface).

Component video will be the more common connection for most progressive-scan DVD players and cable/satellite HD tuners. However, both DVI and HDMI have become more and more commonplace in the world of HDTV. While image quality is identical between DVI and HDMI, HDMI carries both video AND audio, unlike DVI and component video. In addition, since "smart" HDMI cable supports two-way communication between devices allowing you to remote control your connected audio video system. As more and more HD sources - Blu-ray and HD-DVD players -- come to market, HDMI is mounting a campaign to be the high-def input of choice, so make sure your HDTV boasts at least a couple of HDMI inputs.