So what do consumers need to know when shopping for a new set? Unfortunately, the technology is a mystery to most of us, and the marketers have already cluttered the landscape with an array of confusing terms and promises only decipherable by the hardcore techies among us. We'll try to boil it down to the basics and get you pointed in the right direction. Look at the pros and cons described below, consider how you watch TV (types of programs, casual, home theater, etc), and weigh the cost. Know what to look for and the choices seem a lot simpler.

Digital Television Formats

    Digital TV (DTV) is a generic reference to television signals that are broadcast in digitally coded form. The same bits and bytes that brought on the computer revolution now promise dramatically improved pictures presented on a new-sized screen that is shaped more like a movie theater screen with compact disc quality sound. In its highest quality form, the digital signal results in what has been dubbed HDTV, or High Definition Television. In this highest resolution mode, both pictures and sounds reach startling levels of clarity. But being digital does not necessarily mean being high definition. In fact, the majority of digital source material to be viewed on your television, be it DVD, cable, satellite, or over-the-air broadcast, is not transmitted in HDTV format. There are essentially three levels of digital televisions available on the market today. They are: Standard Definition (SDTV), Enhanced Definition (EDTV), and High Definition (HDTV). Let's look at what each brings to the table.

Standard Definition (SDTV)

    Standard Definition can be likened to your conventional television gone digital. Its screen shape, also known as aspect ratio, is the same as what we're used to, and the number of lines that are scanned across the screen (the resolution) to make up the picture is roughly the same (480). Just as in our analog televisions, the lines used to produce the picture are not displayed all at once. Rather, two pictures are actually created that, when combined, produce the full picture we see on the screen.  Picture one consists of the odd numbered lines and picture two the even numbered lines. It takes 1/60th of a second for each picture to be displayed. Some quick math shows us that the full picture is then displayed in 1/30th of a second. This combination of the two images to produce the whole is called "interlacing."  The two images are "interlaced" together in a display referred to as 480i. This system has always had some inherent problems like "flickering," where the picture does not appear entirely stable, "motion offsets," where the edges of each of the bits that make up the picture appear jagged, and "line visibility," where we can actually see fine horizontal lines that run across the screen when the picture is displayed. When screen sizes were small these were hardly noticeable, but as screen sizes got larger these inherent weaknesses became quite visible to even the casual viewer. Analog or digital, many of these problems are inescapable in a 480i display.

    This system was originally created to save on "bandwidth," the imaginary pipe through which all this information flows. Since only 1/2 of the picture was actually being transmitted at a time, the bandwidth available did not have to be so large. With the advent of faster ways to read and write information, DVDs for example, this limitation disappeared. We can now draw all of the scan lines sequentially from 1, 2, 3…up to 480 on one pass. This eliminates the "flickering," removes the jagged edges, and reduces the visibility of the scan lines. This technique is called "progressive scanning." This 480-line progressive scan technique is commonly referred to as 480p or Enhanced Definition TV (EDTV).

Enhanced Definition (EDTV)

    EDTV, or 480p, provides a significant improvement in picture quality, but in order to take advantage of 480p, you need a source that produces a progressive scan output. Fortunately, most newer DVD players offer this feature. What about pictures from VCRs, cable, or broadcast television that aren't in progressive format? Ingeniously, the engineers have built circuitry that de-interlaces these pictures through circuitry called line doublers. This little piece of electronic magic essentially takes a 480i signal, recombines the lines in sequence, and displays that picture to the screen twice in that same 1/30th of a second we mentioned earlier, resulting in a 480p signal. As an added bonus, a good line doubler will also look for motion offsets (remember the jagged edges) and attempt to smooth them out. Most EDTVs from high-quality manufacturers can actually produce a much better looking signal than they started with through the intelligent design of these line doublers. Short of HDTV, this is perhaps the biggest leap in quality that has sprung from the digital television revolution. DVDs played with a progressive scan DVD player and shown on a progressive scan TV can offer pictures of startling quality. But it's still not High Definition TV (HDTV), and that's where all the hoopla is.

High Definition (HDTV)

    HDTV does two things to make the leap to its current status as the "ultimate" television. First, it changes the shape of the picture screen (aspect ratio) to mimic that of the movie theater screen. The ratio for HDTV screen shape is written as 16:9, frequently referred to as "widescreen," where the conventional TV screen shape is called 4:3. (Do not be deceived by conventional aspect ratio TVs claiming to be HDTV. They may manipulate the image in a attempt to create a widescreen appearance, but this does not meet the standards of true HDTV). Second, it increases the number of lines displayed on the screen for each picture. To further complicate this otherwise simple increase in the number of lines, there are actually two different methods used to increase the line count, and both qualify as HDTV.

    Method one uses 1,080 lines interlaced, or 1080i. From our earlier discussion of the problems that interlacing can bring to a picture, you'd expect this to be a problem here as well. In fact, the dramatic increase in the number of lines (from 480 to 1,080) makes the problems of scan line visibility virtually disappear and reduces the visibility of the jagged edges caused by quick motions in the picture. There has recently been introduced more tv models displaying 1080p (1,080 lines displayed progressively) to the market. This may be the future of HDTV as high-definition sources like Blu-Ray formats eventually make it to the home market, but for now they are at the expensive end of the HDTV spectrum.

    Method two uses a line count of 720, but displays them progressively, as explained in the EDTV section above. This system is referred to as 720p. Even though there are fewer lines than the 1080i format, the use of progressive scan eliminates the motion offsets (jagged edges) that still exist in any interlaced format making it particularly adept at handling rapid motion pictures like sporting events. Both systems qualify as HDTV and both are excellent methods of displaying high-quality pictures. Deciding between the two can be difficult. In theory, if you watch a lot of high-action sports or movies, 720p can handle it better than 1080i. In fact, many of the sports networks broadcast their HD programming in a native resolution of 720p. On the other hand, the extra lines of resolution available in 1080i (or 1080p) can yield a quality of depth and clarity on more typical images that is unrivalled. The choice is one of riches. In reality, either format will produce startling images when an HDTV signal is available for it to display.

Types of Televisions

    So, what about being flat? Aren't HDTVs flat panels that look like something out of the Jetsons? Not at all. The development of different kinds of television "tubes" has progressed just about as fast as the digital revolution. In fact, the newer technologies don't use "tubes" at all. Let's take a look at the four most common forms of television displays available to consumers: Cathode Ray Tube (CRT), Rear Projection, and Flat Panel..

CRT

    CRTs are essentially the same picture tubes we've grown up with since the birth of television. They are a proven commodity. When well designed, they produce excellent colors, brightness, contrast, and longevity. Short of massive screen sizes, they are economical to produce. Why ask for anything more? The answer, in a word, is "size." CRTs are big and bulky. As the screen size increases, so does the depth of the tube. As screen sizes grew from 19" to 25" to 30" to 36" and more , the size of the televisions and their cabinetry became massive. Manufacturing and design improvements have helped some, but CRTs remain large. Whether direct view or projection, analog or digital, the vast majority of televisions that have been sold are based on CRT displays. CRTs are, however, quickly fading away.

Rear Projection

    Rear projection is not a display device in and of itself, but a way to use existing devices to produce a larger picture than they would display directly. In the past, projection TVs were based on a set of CRTs (one red tube, one green tube, and one blue tube) combined with high-quality lenses and mirrors to enlarge the picture and reflect it onto a screen. Improvements in this display system ushered in the home theater revolution, with bigger screens and better pictures year after year. The problem for many was the massive size of these TVs. As screens reached ever larger sizes, some projection TVs wouldn't even make it through a standard doorway to get them into a customer's home theater. Improvements in technology and construction have allowed many of these ubiquitous home theater necessities to slim down quite a bit. Additionally, there are breakthrough rear projection TVs now being offered in increasing numbers that do not rely on CRTs for their primary display but rather on newer Liquid Crystal Display (LCD) and Digital Light Processing (DLP) systems. These approaches offer more dramatic improvements in box size vs. screen size and, particularly in the case of the fast developing DLP system, at very competitive price points. With any of these display technologies, rear screen projection systems will continue to provide the most bang-for-the-buck to customers looking for big screen sizes and high-quality pictures.

Flat Panel

Liquid Crystal Display (LCD)

    Liquid Crystal. Well which is it, liquid or crystal? Amazingly it's both. These seemingly magical little twisted crystals can behave as both solids and liquids. They transmit light and they respond to electric current. Put it all together with a red/green/blue filter, some transistors and capacitors, and an external light source, and we've got a very thin screen that will display our television and video pictures. Hang it on the wall and we're in the 21st century. Isn't science great? There are, however, a few drawbacks that engineers are still grappling with. These wonders of nature and science are not particularly efficient. A lot of light is lost in the display process, and since they rely on an external flourescent backlight source to work, providing adequate light intensity and the subsequent cooling required for such a light is quite a challenge. With so much light required, there is also the difficulty of blocking the light completely to render truly dark blacks for picture contrast. On the flip side, since the crystals themselves are somewhat passive participants in the picture display process, when you replace the light source, you're theoretically back to new condition. Additionally, LCD sets suffer from a problem best described as motion-lag. Fast motion can result in blurring of the image. But engineers love a challenge and LCD TV displays are becoming larger, better, clearer, and cheaper. New options for backlighting using LEDs (light emitting diodes) are hitting the market. If these LED/LCD displays live up to their hype, colors will be brighter and blacks will be blacker and the problems of diminished light output from an aging bulb and bulb replacement will be eliminated. Increased refresh rates and motion compensation circuitry, usually described as 120Hz technology, are minimizing the blurring of fast motion and increasing the detail of LCD displays. Many believe that some variation of the LCD display will be the prevailing challenger to the standard technology of affordable large screen TVs, despite the early strides of a competing flat panel technology known as Plasma TV.

Plasma Display TV

    Plasma is different from other TV display technologies. Charged electrodes between glass panels cause tiny pockets of inert gas to change into a state of plasma. This process causes UV light to be produced, which in turn reacts with the red, green, and blue phosphors in each pixel to produce visible light. No scan lines, no external light source, good pictures and brightness when watching at an angle to the screen (off-axis viewing), and pretty good color saturation. In theory, a perfect picture across the screen with exceptional sharpness and brightness. Sounds perfect. Well, almost. Plasma has some bugs to be worked out. Foremost is its problem dealing with the non-color, black. Even some of the best plasma displays have trouble rendering a true black. Instead, we have to settle for some shade of very dark grey. Although better than LCD technology, there is work to be done in this area. There is also a little problem with green. This one's a bit weirder. The problem is that plasma produces a green that is not the one we're used to, our old friend CRT phosphor green. If not dealt with adequately, some pictures just look odd. Plasma also has a fear of heights. The atmospheric pressure at high altitudes is not to its liking. You'll experience a pronounced buzzing sound should you install one in your Colorado mountain top lodge. You must also be very careful of "burn-in." Programs with bright logos or persistent static images can produce a permanent "ghost" of the image on the screen. Oh, and did I mention they're still quite expensive? But...they're just so cool. Cool or not, the technology is improving rapidly. It has captured the imagination of the public and recent advances promise to continue the trend of significant price reductions. A good, very cool TV now, plasmas have a way to go to combine value, quality, and attitude.

LCoS Display TV

    Liquid Crystal on Silicon (LCoS), has enormous promise to develop CRT quality images on a flat screen display. It has, however, proven such an expensive and difficult technological undertaking that most manufacturers have abandoned it, leaving (at the time of this writing) Sony as the only major player still attempting to realize its full potential.

How to Shop

Test with B&W: The true test of the clarity and definition of a television is how well it renders black and white. Fuzziness and lack of contrast will be immediately apparent on a black-and-white image, where it may be more difficult to perceive in color. This can also show you defects in rendering a "true" black. Is black really a muddy grey? Here's a tip. Test your prospective TV purchase with a high quality black-and-white recording (one of the classic movies, for instance) on DVD and look for clarity. Only then take a look at the color.

They Set Them Hot: Televisions frequently arrive at the retailer with the internal color settings adjusted to be "hot,'' or oversaturated, when the manual adjustments are set to "normal.'' Don't rely on the "normal'' or "center'' positions of your controls for proper adjustment. The professional way to set "correct'' color is to use a SMPTE Color Bar pattern and a blue filter. For general purposes, however, use the highest resolution source you have available (typically a well mastered DVD) and set the flesh tones to appear natural. Realize that this setting will vary between different signals received by your set and is always a compromise. There are also consumer "set-up" DVDs available like the Sound & Vision Home Theater Tune-Up, Digital Video Essentials, and The AVIA Guide to Home Theater that can be quite useful in calibrating your TV for a better picture. Ultimately, a professional alignment can provide significant improvement in the natural rendering of colors on most larger sets.

Don't Get HDTV Suckered: As you've read above, all digital TVs are not HDTVs. If you're looking for a true high definition display, it must be a 1080i, 1080p, or 720p display and have the widescreen, 16:9 aspect ratio. If it doesn't, it's not a true HDTV.

Visit an Old Friend: Nothing can make the audition process easier than spending time viewing a favorite DVD. You know the one you've watched over and over. You know what to expect. You know what you're used to seeing. You'll see how the set performs with the type of program you like to watch. Don't settle for a quick demo of a reference DVD produced especially for demonstration purposes.

Get Jacked Up: The different types of connectors (or "Jacks") into which to plug your video and audio sources can be a point of much confusion. It is important to think about these available inputs for possible future applications, even if your current DVD player, camcorder, digital camera, etc. don't yet utilize many of them. With the proliferation of devices that you might now expect to plug and unplug from your TV, such as digital cameras, game systems, camcorders, etc., you may also wish to be sure the appropriate connectors are available on the front of the television you're considering.   Let's take a look at the various connector types, starting at the bottom and working our way up the quality scale.

    Which should you have? At a minimum, Component Video connections. These are now fairly standard on quality TVs and video components. If you want to maximize your picture quality, simplicity of hook-up, and future compatibility, multiple HDMI connections are a must.

Hear Here: There is no specification you can check for sound quality, which can vary from quite good to awful. You'll have to judge it on your own. The easiest way to evaluate the sound is to listen to the set with a program of demanding audio content. Use a DVD with a dynamic sound track: loud louds, soft softs, strong bass, and individual voices. Play it at a slightly louder than normal level. Does the sound distort? Do the speakers buzz? Is there any bass? Are the voices clear? (These considerations are only relevant if you plan on using the television's speakers and amplifier. If you are going to run the audio through your home stereo or theater system, see our section on Audio/Video Receivers.)

Check the Angles: The nature of the view screen can cause brightness to decline dramatically as the viewer moves away from a position directly in front of the screen. Simply increasing overall brightness to compensate for this problem may produce a "hot spot'' in the picture's center. A good set may have some dimming as you move away from center, but the picture should still be acceptable for those viewers sitting in less than the "sweet spot.''

Lighten Up: Since the picture on a projection TV is viewed indirectly, brightness can deteriorate. This can be especially troubling in a brightly lit room. Brightness is typically measured in foot lamberts (FL). Usually, the higher the rating for a particular screen size, the better, assuming it is not accomplished by trading off other important elements of picture quality.