Analog TVs send a signal telling the television's electron gun how to "paint" lines on the screen. The problem is that the signal degrades in transmission, affecting the amount of fine detail in the image. Digital sets send this same information in bit streams (lines of data made up of ones and zeroes). The advantage is that these digital signals do not degrade, so the picture is much better on a digital set.
You should also consider the source. No matter how much money you spend on a TV, the picture will only be as good as the source signal it receives. For instance, a DVD will look better on a low-end television than an analog broadcast antenna signal will look on a high-end HDTV. That is because the quality of the digital signal sent to the analog set is far superior to the analog signal sent to the digital HDTV.
Sources break down like this:
The key when thinking about sources is to match the right TV with the source available to you.
Analog signals received on an analog set will display standard-definition TV and cable with a resolution you're probably used to seeing. A digital cable signal (like DirecTV or Dish Network) can be displayed on an analog TV, but it will lose its quality in the conversion from digital to analog.
Digital signals on a digital TV (DTV) will allow you to watch digital broadcasts and progressive-scan DVDs at their full quality. In addition, you will be able to watch most hi-def broadcasts. Enhanced-definition TVs (like plasma TVs) will also benefit from a digital source, but they won't have enough resolution to do HDTV broadcasts justice.
Hi-def broadcast sources will look best when viewed on an HDTV. Here's a breakdown of source/display combinations:
When thinking about whether now is the time to go high-definition, here are some things to consider:
Many stores feature what they call HDTV. What they should say (and some do) is "HDTV-ready." Even though a TV has HDTV capabilities, it still can't receive high-definition input without a
, which can be pricey if you choose to buy one (as opposed to renting one from your HDTV broadcast provider).
HDTVs come in two formats:
1080i is capable of 1920x1080 resolution (the highest currently available), but it is an interlaced format: The TV paints every other line of the image in alternating patterns, so it cannot display progressive-scan DVDs. Also, some critics claim that while still images are more brilliant at 1080i, movement doesn't read well on the screen.
720p turns out a resolution of 1280x720. While lower than 1080i, it still remains the most common HDTV format. Only the most discerning of videophiles can tell a difference in quality, and since it is a progressive-scan format (the TV paints every line of the image in order), it can be used for both standard and progressive-scan DVDs.
At this point, some primetime shows and sporting events are simulcast in hi-def. But if you're in an area that does not receive hi-def broadcasts, then this does you no good. There are close to a thousand hi-def stations on the air in the United States as of May 2004. For a list, see HDPictures: HDTV On the Air!.
Because HDTV broadcasting is still fairly limited, DVD viewing is the big selling point for HDTV. If you put a progressive-scan DVD player together with an HDTV, the results are breathtaking. Most people who are buying HDTVs are doing so to reap the full benefits of their progressive-scan DVD player. It is possible to get into an HDTV for around $700, so if you're a serious movie buff, it may be time to make the switch.
Normal television will look a little better on an HDTV, but don't expect miracles. In fact, on a larger-screen HDTV, the set will actually reveal the imperfections of an analog broadcast. Keep this in mind.