A Word about Visual Tech

I’m sure that many have heard of the latest craze about high definition and all of its attributes. Much of the country will become much more familiar with these terms when all cable providers will switch their signal from analog to digital starting in February 2009. But then again, what are those attributes and what do they mean? What’s the difference between 480i, 720p, and 1080p? How can you watch programming and movies in these different formats? It is my hope that I can dispel some of the confusion surrounding these items and more.

First though, a word must be had about the history of high definition. Surprisingly, high definition technology has been around since the 1980’s in Japan. Much of the craze over high definition here in the United States has been limited to the past ten years. Like many cultural and technological phenomena, we Americans seem to be at the end of the line before any of the latest and greatest makes its way here. To further demonstrate this, even by the late 1980’s, the Japanese had developed an analog signal to broadcast high definition programming. But on the other hand, our flat screen computer monitors are high definition.

That then brings us to the difference between digital and analog, as it may be central to some when the big switch over occurs in February 2009. Currently, many still receive analog broadcasts in regard to their television viewing. Analog technology is actually an “analog wave.” For example, when a television broadcasting station beams out an analog signal from a TV tower to a receiving device, the wave is in its original form. Digital technology on the other hand uses the original analog wave, but that wave is sampled at a given interval and turned into numbers. For example, a digital signal can be found within a compact disc, DVD, or Bluray Disc. On a CD, 44,000 numbers are stored per second of music. In sum then, an analog signal has limitations in size, but digital technology allows for the 0’s and 1’s (the information) to be compressed and error free, hence more clarity.

What does that have to do with 480i, etc…? First off, because a digital signal can carry more information than that of an analog signal, it allows us to view TV and movies in life like high definition. For example then, most television viewing is done in 480i, as it is in analog form and can only carry a limited amount of information in the signal. What exactly is 480i and such?

-480i: This is called “standard definition” and can only display a limited number of horizontal and vertical lines on your television.
-480p: This is what you would see when you view a standard DVD; a few more horizontal and vertical lines.
-720p & 1080i: These two formats are called “high definition.” These formats are broadcast in a digital signal due to the increased data, which in turn provides for more horizontal and vertical lines. -1080p: Known as “true HD,” 1080p is also broadcast in a digital signal and provides for the best picture possible.

The easiest way to think of the above is through the numbers. For example, there is a 360 horizontal and vertical line difference between 720p and 1080i. 1080p on the other hand can refresh the line rates in your TV at a much faster rate (hence the “I” and “p”). When the digital signal become standard, you are not going to be able to view high definition or true HD on your tube TV (if it has a digital tuner), as the TV is not capable of producing the number of lines required. You would have to purchase an LCD or a plasma TV in order for that to happen. If your tube TV is a bit older and does not have a digital tuner, you can acquire a converter from the government or from a cable company that will convert the digital signal into a usable form by the TV.

There are more nuances to be discussed, but I’ll leave it at this stage for now.