HDTV Full Story

HDTV Fundamentals

Not that long ago, TV was TV. There was one main technology (direct-view cathode ray tube, or CRT) and one broadcasting format (480i). Now, however, there are five different types of TV and a number of different technologies. There are also lots and lots of different ways to format a TV signal. In fact, the Advanced Television Systems Committee (ATSC), which is the organization that created the digital broadcasting standards for the United States, allows 18 in all. Fortunately, there are "only" five that you really need to be concerned with:

480i Standard Definition (SD). To create an SD picture, 480 horizontal lines of image information are sent in an interlaced (that's what the "i" stands for) format. Each frame (or image) of an interlaced TV signal is actually made up of two fields, one consisting of the odd lines of the image and the other the even lines. The two fields are displayed one after the other by the TV at a speed that's so fast that the eye sees only one image. SD images have the familiar 4:3 aspect ratio.

480p Enhanced Definition (ED). Like standard definition, a 480p EDTV image is made up of 480 lines of information; however, they are displayed in a progressive format (hence the "p"), which means the entire frame is displayed at one time. While there is no more image information than in an SD picture, the image appears sharper and smoother because the artifacts caused by interlacing are eliminated. While ED sets cannot display HDTV signals in their full resolution, they are usually widescreen.

720p HDTV. The lowest of the high-definition resolutions, a 720p image is made up of 1280 x 720 pixels displayed progressively. While other formats display more picture information, many critics say that at normal viewing distances, this format presents a picture that's just as appealing and even more film-like. Among major programmers, only ABC and its subsidiaries (including ESPN and ESPN2) and FOX distribute content in 720p.

1080i HDTV. This format places 1920 x 1080 pixels of picture information on the screen (in an interlaced format) for a vivid and sometimes breathtaking picture. Most broadcast, cable and satellite HD providers use this format.

1080p HDTV. Most new HDTVs are capable of accepting 1080i signals and, after some internal processing (called de-interlacing), these TVs can display the signals in a progressive format for the richest images of all. Most of these sets (but not all) are now also capable of accepting 1080p signals from high-quality sources such as Blu-ray disc players. Because it takes up so much bandwidth, it is unlikely that any broadcaster or other programming provider will be distributing HD material in 1080p in the foreseeable future. So right now, 1080p is mainly a media format.

Note that while ATSC-compatible tuners must be able to receive all ATSC formats, the TVs themselves are free to take those signals and scale them to fit their native resolutions, which, for manufacturing reasons, don't always match up exactly with the ATSC standards.

The bottom line, however, is that regardless of the resolution, HDTV looks terrific compared to SD or EDTV, reviewers say. But it doesn't take an expert to see the difference. If you look at an SDTV next to a HDTV in a store, you'll immediately notice why high-definition TV is so compelling.

HDTV content used to be an issue, but that is no longer the case. Programming is much more available, and the major networks now broadcast virtually all of their prime-time programming in HD. There are also lots of HD cable networks, and that number continues to grow. Most cable and satellite companies are in a race to add HD networks to attract and retain subscribers. All of that, coupled with the fact that prices for HDTVs are dropping fast, means that HDTV is no longer merely for videophiles.

Simply buying an HDTV does not automatically mean you get HDTV images on your screen. The hardware is only one part of the equation. To get the high-definition programming signals, you need to subscribe to a digital high-definition cable or satellite service. Alternatively, you can receive HDTV broadcasts "over the air" with a roof-mounted or even an indoor antenna, provided you are within range of a transmission tower. Of course, you won't get premium channels this way, but you can access the local affiliates of the major networks. AntennaWeb.org is a great website that lets you plug in your home address to see what kind of over-the-air broadcasts are available in your area, and what kind of antenna you'll need to receive them.

With all TVs now required to have digital tuners, HD-ready sets (those that can display HD images but lack an integrated digital tuner) are all but gone from the market, with some notable exceptions. The law requiring new TVs to have a digital tuner does not apply to monitors -- those TVs that have no tuner at all. Tunerless monitors can be a good choice for those who get all of their TV from cable or satellite, but you'll need an external tuner to get any over-the-air programming. Most front projectors also lack TV tuners of any kind.

Some HDTVs are compatible with CableCards. These TVs don't require a cable box to receive premium programming from cable companies. You plug the digital cable feed directly into the TV, and your cable company installs a CableCard (which goes into a slot on the TV). The CableCard de-scrambles the channels to which you've subscribed. However, experts' reactions to first-generation CableCards have been lukewarm, mostly because you can't use any of cable's interactive features. You can't order movies on demand with the remote or access the interactive programming guide.

Tru2way, a new two-way standard for delivering scrambled programming and passing interactive content -- such as the program guide -- to compatible TVs without a cable box, is gaining acceptance by both manufacturers and cable providers. Sony, Panasonic and Samsung are among set makers that have announced that they will support it, along with at least six of the largest cable companies in the nation, including Comcast and Time-Warner. However, there's no firm word as of yet as to when sets with the technology will reach store shelves, or when cable rollouts will begin.

Cable subscribers might also be interested in sets with QAM-compatible digital tuners. QAM, which stands for Quadrature Amplitude Modulation, is the transmission scheme cable companies use to distribute digital TV signals. A QAM tuner can allow you to receive any unscrambled, basic programming you subscribe to without a cable box or CableCard, so that's one less piece of hardware you'd need. An external box or a CableCard is still required for premium programming, however.

While the analog broadcasting system will be gone for good in February 2009, those with older, non-digital sets will not be left completely in the dark. Cable companies are being required to provide local broadcasts to analog TV owners who subscribe to basic cable (which doesn't usually require a set-top box) until at least 2012. Providers have the choice of converting the digital broadcasts to analog for distribution on their systems, or providing all of their customers with free converter boxes.

In addition, the government has set up a voucher program that will help offset some of the cost of an external digital tuner for those who need them. The program, which began this past January, provides $40 coupons that can be used toward the purchase of up to two analog-to-digital converters. While funding for the program is limited, coupons were still available as of August. See Best Research for more information.

TYPES OF HDTVs

There are four main types of display technology for HDTV. Plasma and LCD TVs draw lots of attention, as these two types are wall-mountable. LCD flat panels come in smaller, less expensive sizes, while plasma TVs are only available in sizes larger than 32 inches. Rear-projection TVs have come a long way from the huge cabinets you might remember. These newer microdisplay models cut down on the depth, but still deliver big screens up to 70 inches. However, rear-projection sets are decreasing in popularity as more and more buyers opt for sleeker flat-panel displays. A last option is hooking a front projector up to your cable feed and projecting the image on a wall or, preferably, on a screen. Conventional tube-based TVs are still being made, however all are standard definition.

Flat-panel plasma and LCD HDTVs

Plasma and LCD TVs are only a few inches thick -- and sometimes less -- and are wall-mountable. Design-wise, most look terrific hanging on a wall or sitting on a tabletop. Plasma TVs come in screen sizes of 32 inches and up (measured diagonally). While the most common sizes are 42 inches and 50 inches, larger plasma displays are becoming more commonplace, as are sizes such as 46 inches, designed to directly compete with LCD screens of the same size.

LCD TVs, on the other hand, are available in a much wider range of sizes. The smallest LCD TVs are about 8 inches, and sizes for consumer TVs now go up to 65 inches, with some manufacturers demonstrating sets as large as 108 inches. Smaller LCD flat-panel HDTVs, which start at around 19 inches, are a good choice for bedrooms and kitchens.

The advantage of plasma and LCD TVs, of course, is a sleek screen that takes up very little space. But note that while they may be thin, larger flat-panel TVs are still quite heavy and wall mounting often requires professional installation.

Smaller LCD TVs have a native resolution of 1366 x 768 pixels. LCD TVs with that resolution can display standard TV, DVDs and 720p HD with no loss of detail, but need to scale down 1080i HD programming. Manufacturers have been rushing 1080p sets to market in more and more screen sizes, down to as small as 32 inches. These LCD TVs are more expensive than 720p TVs, but they can display every pixel of a 1980 x 1080 HDTV image.

Likewise, many new plasma TVs have 1080p resolution. While initially more expensive than their LCD counterparts, prices have closed for all but the most expensive models. Manufacturers are also continuing to produce 720p plasma sets, and these make great budget performers. Note that while most 50-inch and larger 720p plasma TVs have the same 1366 x 768 resolution as LCD, 42-inch 720p plasma TVs typically have a native resolution of just 1024 x 768 pixels, which falls short of the ATSC standard of 1280 x 720. Despite that, industry convention -- which only looks at the horizontal specification when labeling TVs for sale to the public -- allows them to be sold as HDTVs. While this is an issue with some, reviewers say that as a practical matter, few will be able to tell the difference between 1024 and 1280 vertical resolution at normal TV viewing distances.

While experts say the gap is closing, plasma TVs are known for their ability to display dark colors and detail in dark scenes better than LCD. This makes plasma a good choice for movie watching, where dark scenes are common. LCD TVs are brighter, which means LCD may be a better choice for a well-lit setting; plasma TVs can sometimes look washed-out in a bright room.

Plasma screens have wider viewing angles than LCD flat panels. That means you can sit at more of an angle and still get the best picture. With conventional TVs, the picture brightness and color saturation stays the same from virtually any angle. With LCDs, sitting too far to one side will result in a loss of brightness. In addition, LCDs can sometimes leave trails behind fast-moving parts of an image. That's because of the time it takes for LCD pixels to switch color (plasma pixels make the change much faster). Finally, slower LCD switching speeds sometimes cause a loss of detail in fast-moving images. However, technology improvements have made both viewing angle and motion trails less of an issue in better LCD sets, and new technology to address softness in action scenes is included in many of the newest LCD TVs, though we've seen mixed reports of its effectiveness, and even its need.

The most disconcerting issue regarding plasma TVs in the past has been a susceptibility to burn-in. Leaving the same image on the screen too long risked its being etched permanently into the screen, creating a lasting impression. New technology greatly reduces the risk of burn-in, and analysts at PC Magazine say that burn-in is no longer a major concern. Still, it's a good idea not to leave a plasma TV on when you're not watching it. LCDs have no burn-in risk. Temporary image retention -- a related but less severe problem -- is still a concern, however, and some plasma TVs, particularly budget options, can maintain ghostly shadows of previously displayed static images for minutes or more.

While plasma TVs can produce great, cinematic images in a darkened room, they sometimes appear washed out when room lighting is higher. In addition, their top glass is usually much more reflective, though plasma TVs with anti-reflective screens are also available. Because of that, LCD TVs are sometimes a better choice for viewing in areas such as a typical living room where there are windows, making for greater variation in lighting at different times of day or night. However, some top-rated LCD TVs are now using more reflective glass as well.

Though some buyers have been concerned about the life expectancy of a plasma TV, the latest models have panels that are rated to last up to 60,000 hours before they lose half their brightness. That translates to over 20 years if you watch TV eight hours a day. Until recently, plasma TV held a price advantage over LCD, but that gap is closing. In addition, if you want 1080p resolution, LCD is often a slightly less expensive option.

As discussed in our report on plasma TV, the best choice right now is the Panasonic VIERA TH-46PZ800U (*Est. $2,175) . If your budget is a little tighter, the Samsung PN50A550 (*Est. $1,660) deserves some serious consideration.

Among LCD TVs, Samsung has received great acclaim for its Series 6 1080p LCD TVs, including the 52-inch Samsung LN52A650 (*Est. $2,400) , 46-inch Samsung LN46A650 (*Est. $1,745) and the 40-inch Samsung LN40A650 (*Est. $1,450) . Sony's BRAVIA line of 1080p LCD HDTVs also does very well in professional reviews. Models include the 40-inch KDL-40XBR4 (*Est. $1,930) and 46-inch KDL-46XBR4 (*Est. $2,400) .

Rear-projection TVs

Thanks to the popularity of flat-screen LCD and plasma TVs, rear-projection TVs have become an afterthought in the marketplace. However, some still-attractive performers remain available, and rear projectors deliver the biggest screen sizes at the lowest cost per inch of all HDTVs.

Today's rear-projection TVs are microdisplays, which get their name from the fact that their cabinets are so much smaller than the CRT RPTVs they have displaced. Even the largest are less than 16 inches deep, and smaller sets are shallower still. While that's certainly too deep to hang on a wall, it's a far cry from the CRT-powered behemoths of yesteryear.

Until recently, four different rear-projection technologies were competing for floor space. However, all have given way to one -- Digital Light Processing, or DLP. DLP projection TVs direct light through a spinning color wheel onto nearly a million tiny mirrors that are used to project the image onto the screen. One problem with that technique is what's called "rainbow effect," which appears as a multicolored shadow around an object in certain scenes.

Fortunately, only a very small percentage of the population can see rainbows in the first place, and advances in technology have made it less of a problem still. Even some of those afflicted say that an occasional rainbow doesn't bother them, but others say it wrecks the TV-watching experience and, in the worst cases, can cause eyestrain, headaches and the other symptoms. In any case, spending a bit of time auditioning a DLP set in a showroom might not be a bad idea if you are unsure if you are one of the unlucky ones that sees rainbows.

Among rear projectors, critics and users uniformly point to the 61-inch Samsung HL61A750 (*Est. $1,850) as the top choice. That TV does away with the standard lamp and replaces it with colored LEDs. One advantage to that is longer lamp life. While most lamps last around 3,000 hours, Samsung expects its LED light engine to last 60,000 hours. Another is that rainbows are minimized, though apparently not entirely banished for those most able to see them. If 61 inches of HD image aren't enough for you, the set is available in a 67-inch model as the Samsung HL67A750 .

Front projectors

Once a part of only the most expensive home theater setups, digital projectors have dropped in price to where they are now a practical option. But while these projectors are capable of delivering the largest images (over 100 inches) at the lowest cost (on a dollars-per-inch basis), critics note that they are not perfect for everyone or every situation.

For one thing, they demand more from the user. To complete your home theater, you need to supply a screen (for best results) and an external audio system. Also, since projectors don't include their own integrated tuner, you need to supply an external one or a signal from a cable or satellite TV box.

The second issue is light levels. For the most part, digital projectors are only suitable for use in rooms where lighting can be completely controlled. That's because even a little bit of ambient light can wash out the image. This is less of an issue with brighter projectors, but still, front projectors are not the best choice for daylight viewing in a sunny room.

Front projectors using three different technologies are available. DLP front projectors have the same drawbacks (i.e. rainbow effect) as rear projectors, but also have exacting placement requirements that can make using them difficult in some viewing rooms. LCoS (Liquid Crystal on Silicon) projectors are lauded for their great picture quality, but are very expensive. LCD projectors offer great colors, but in the past were plagued with light black levels and an artifact known as "screen-door effect." However, advances in technology have boosted blacks to the point where they are competitive with other projectors and have essentially eliminated screen-door effect, especially at typical viewing distances.

The biggest news in front projection has been the tremendous price cuts. Three years ago, a 1080p projector would have cost around $30,000. Today, a top-performing 1080p projector can be had for under $3,000. One example is the Panasonic PT-AE2000U (*Est. $2,700) , a 1080p LCD projector that has reviewers doing cartwheels over both the price and performance. Reports say that black levels, sharpness and color are truly first rate. In addition, the projector has tons of adjustments and built-in calibration features that make it possible to tweak things to perfection. A long zoom range and lots of lens shift means placing the PT-AE2000U is a snap in any setting. While some other projectors are brighter, this Panasonic projector can still produce a great image of over 100 inches.

For those looking for an inexpensive option, the Optoma HD65 (*Est. $800) has earned praise from all quarters. Reviews say that the 720p DLP front projector doesn't have the best blacks, but that they will satisfy most, and that colors and brightness are great. The biggest drawbacks are this projector is more likely to throw out DLP rainbows for those who can see them, and installation can be tricky. The biggest plus is the tiny price tag.