How to Buy a Flat-Screen HDTV

The Specs Explained

Buying an HDTV requires more than just deciding how big a screen you want, looking at some sets, and purchasing the one with the best picture that fits your budget. An options explosion has littered the shopping landscape with numbers, features, and terminology that even experts sometimes have trouble tracking (not us, though). We've cut through the chaos to give you the information you need to get up to speed. When you're finding your way in the high-def, A/V world, don't just go for the gaudiest numbers--some are important, sure, but others aren't. Let's quickly walk through a few.

Important: Contrast Ratio

Contrast ratio refers to the brightest and darkest light values a display can produce at the same time. All else being equal, the higher the contrast ratio is, the better the quality is. All else is seldom equal, however.

Pumping up the maximum light output, for example, will increase contrast, but it won't do anything to help pitiful black levels--that, in our opinion, is a much greater concern. LCDs in particular have a tougher time dealing with darks. So take contrast ratings as a very rough guide to be supplemented by eyes-on evaluation. LCD contrast-ratio specs start at about 600:1, while those for plasmas start at about 1000:1. Although ratings of 10,000:1 or better are becoming common for both types of displays, you should approach such claims with a healthy bit of skepticism. Since no true standard method for measuring contrast ratio exists, manufacturer exaggeration is rampant. Independent reviews are a more reliable guide, but in the end you need to trust your own eyes. Keep in mind that when you're on a showroom floor, you're checking out the HDTVs under the store's lighting conditions, not yours. Will you watch in a dark cave or in a well-lit, open space? Probably the smartest idea is to check the store's return policy before buying.

Important: Aspect Ratio

The aspect ratio describes the relationship of screen width to screen height. Conventional sets have a 4:3 aspect ratio, whereas wide-screen models are 16:9. Wide screens are the future. For one thing, HDTV is a wide-screen format. For another, DVDs usually look better on wide-screen displays because nearly every movie made in the last 50 years was filmed in an aspect ratio of either 1.85:1 (very close to 16:9, which is 1.78:1) or 2.35:1 (even wider than 16:9).

Important: Video Inputs

The number and type of video inputs determine which sources you can use with the display.

Composite video: This input type has the lowest quality but the broadest compatibility. Any device that has video outputs will include composite video among them. Connection is made with a single 75-ohm coaxial cable between RCA jacks.

S-Video: S-Video offers better quality than composite video does, and most video sources except standard VCRs now have S-Video outputs. Connection is made with a special cable and multipin sockets.

Component video: This high-quality option is the minimum standard for connecting high-definition cable and satellite set-top boxes, as well as progressive-scan DVD and Blu-ray Disc players. It requires three 75-ohm coaxial cables of the same type used for composite video.

VGA (Video Graphics Array): This high-quality analog RGB connection is used primarily for computer connections.

DVI (Digital Video Interface): One of the highest-quality types of inputs. This digital video connection can attach to devices with HDMI outputs (see below) by means of an adapter. It may also be used for computer connections. Requires a special cable and multipin sockets. Some displays with a DVI input may work only with computers, so watch out for that if you plan to connect an HDTV source, such as an HD digital cable box or a Blu-ray Disc or HD DVD player. Another thing you need for guaranteed HDTV compatibility is compliance with the HDCP (High-bandwidth Digital Content Protection) system.

HDMI (High-Definition Multimedia Interface): Also of the highest quality, HDMI is DVI plus a digital audio and control link. HDMI is the dominant digital connection interface for HDTVs today. The big draw here is that you get a one-wire setup that pumps HD content into your other home-theater components too. This connection is provided on almost all current HD satellite receivers, HD cable boxes, and upconverting DVD players (those that provide 720p, 1080i, or 1080p output from regular DVDs), and it is the standard video connector for Blu-ray Disc players. The exact version of the HDMI input (for example, 1.1 or 1.3) is of little consequence on TV sets currently on the market. Of more importance to HDTV shoppers is how many HDMI inputs a TV has. Aim to get an HDTV with at least three or four HDMI inputs, to accommodate the multiple devices you're bound to accumulate.

HDMI CEC: HDMI inputs may include support for the Consumer Electronics Control (CEC) protocol, which enables CEC-certified components to send control information back and forth to one another. This arrangement can allow single-remote--or even single-button--control of functions involving multiple components, such as a TV, DVD player, and A/V receiver. Manufacturers tend to have their own names for HDMI CEC, such as CE-Link (Toshiba) and Anynet (Samsung). In many cases the CEC functionality is restricted to components from the same maker, which obviously lessens the benefit in a mixed-brand system.

Important: Resolution

Non-CRT displays, such as plasmas and LCDs, are fixed-pixel arrays, meaning they have rows and columns of individual picture elements that turn on and off to produce the necessary patterns of light. Resolution is specified as the number of pixel columns by the number of pixel rows--640 by 480, for example, or 1280 by 720. Resolution and contrast ratio determine perceived picture detail.

Digital content currently is delivered in one of five formats: 480i, 480p, 720p, 1080i, and 1080p. The 480i format is the same as that used for standard analog TV, and when programming originally in 480i is delivered by digital cable or satellite to your home, it retains that format. DVDs are sometimes mastered in 480p, but mostly they are 480i; a progressive-scan DVD player can deinterlace 480i DVDs to create 480p output, however. The 720p and 1080i formats are used by satellite, cable, and over-the-air-broadcast high-definition content providers, as well as some advanced DVD players that upconvert 480i and 480p content. Blu-ray Discs output 1080p video, though Blu-ray players can deliver the content in 1080i or 720p format for displays that do not accept 1080p input.

Given that the price differential between 720p and and 1080p has narrowed considerably, we recommend buying a set that supports 1080p. Your new HDTV represents a long-term investment. Some online streaming services, such as Vudu and Dish Networks' on-demand options, are offering 1080p today, and we expect more services to follow in the future. If your budget can handle 1080p, go for it.

Generally speaking, a display is considered high-definition if it is wide-screen and has a total pixel count approaching 1 million. So 1920 by 1080 (1080p), 1280 by 720 (720p), 1366 by 768, 1024 by 1024, and 1024 by 768 are all examples of high-definition display resolutions. The larger the screen and the closer you sit to it, the more important its resolution becomes.

Somewhat Important: Screen Size

Size matters, don't get us wrong. But just because you can afford a 65-inch monster, that doesn't mean you should buy one. You need to factor in the screen size and where you plan to watch the TV. Having your nose pressed up against the display in a broom closet of a room is hardly "ideal viewing conditions."

To determine the best viewing distance, and therefore how much space you'll need in your TV room, remember this simple bit of math: Note the screen size in inches and multiply it by 2. Calculators ready? Take, for example, a 52-inch set. The sweet spot for viewing is 104 inches away, or a little more than 8.5 feet from the screen (8.66666667 feet if you want to be nitpicky about it). You don't have to be exactly on target; simply bear this in mind as you plan where to place your new set.

Somewhat Important: Built-In Tuners

Most current flat-panel displays include a tuner for conventional analog broadcast and cable-TV reception and for broadcast HDTV. A few, however, are strictly business--they're monitors with no built-in tuner (more common for plasmas than for LCDs). That may not matter if you receive all your TV programming via satellite or cable, but if you want to watch broadcast TV over an antenna, be sure that the set you buy includes a TV tuner. Most sets also have built-in tuners for digital cable TV (referred to as ATSC digital tuners). Although such tuners have a standard for handling scrambled premium channels (for example, HBO), many sets do not support it, so be sure you know exactly what you are getting. If you're interested in that capability, you may know about CableCard (a few sets in the recent past offered a CableCard slot). But CableCard is giving way to the new Tru2way standard, which can banish the external box if both your TV and your cable provider support it.

Somewhat Important: Refresh Rate

Refresh rate refers to the number of times per second a new image displays on the screen. The standard refresh rate for television in North America is 60 times per second, or 60 Hz (hertz), and until fairly recently that was it. Now, however, many high-end LCD HDTVs offer a 120-Hz refresh rate. Usually the TV set achieves the higher rate by interpolating new frames between the ones that are broadcast. The tactic helps minimize or eliminate the blurring of fast motion that sometimes occurs on LCDs because of their relatively slow response times (how long they take to switch between black and white or between dark gray and light gray). Done well, 120-Hz refresh can be very effective; but done poorly, motion can appear slightly unnatural. As always, look at a set and judge its performance before you buy. Also find out whether the 120-Hz processing is switchable, so that you can turn it off if you don't like it or you don't need it. As response times and video processing of LCDs improve, the need for refresh-multiplication is diminishing.

Because plasma sets have very fast response times, they don't require 120-Hz processing (though it may start showing up in them simply for marketing reasons). A nonstandard refresh rate presents another potential benefit, however, when you're viewing material that originated as film. Movie film is shot at 24 frames per second and displays in theaters at 48 Hz, with each frame flashed on the screen twice. But putting movies on TV at the standard refresh rate is a little tricky, since 24 does not divide evenly into 60. The conventional solution is to stagger the frame repetitions, displaying the first frame twice, the second three times, the third twice, and so on. Although such 2:3 (or 3:2) processing works pretty well, it imparts a subtle stutter to on-screen motion.

Typically, viewers are so accustomed to this artifact that it seldom jumps out; but once you notice the effect, it's as plain and obvious as can be. The TV can eliminate it, yielding a slightly smoother impression, if the set has the ability to switch to a refresh rate that's an even multiple of 24 Hz for film-based content. Pioneer plasmas, for example, run at 72 Hz for film material, and the 24-fps output options of some Blu-ray Disc players are designed to facilitate the same sort of processing. Since 120 Hz is an integral multiple of 24 Hz, the opportunity exists to do something similar in high-refresh-rate LCDs, depending on how the display's interpolation processing is designed.

Minor: 24p Input

Some Blu-ray Disc players can provide 24-fps 1080p video from their HDMI outputs for discs mastered at 24 fps, matching the frame rate of the film original. If the TV connected to such a player can accept 24-fps 1080p (24p) video and can operate at a refresh rate that is an integral multiple of 24 Hz (such as 72 or 120 Hz), it can process the video to create slightly smoother motion than if it were to convert the footage to the standard 60-Hz refresh rate. The benefit is relatively subtle, however, and not very many TVs offer such processing yet; even some sets that accept 24-fps signals just convert them to 60 fps for display. Be sure you know what you're buying.

Minor: Ethernet Port

Some HDTVs now provide ethernet ports, which can give you access to the Internet or to content (such as pictures) streamed over a home network. Features available via ethernet vary somewhat from manufacturer to manufacturer, so confirm what you're getting before you lay out the cash.

Minor: USB Port

Some HDTVs now have USB ports. Usually they are intended for connecting to flash drives containing pictures, music files, or possibly updates to the TV's internal operating software (firmware). The exact functions of USB ports vary somewhat from one TV to the next, so do some research prior to committing to a set.

Minor: Comb Filter Type

Comb filters are necessary in analog TV to separate color and luminance information without losing too much detail, but that's not an issue in HDTV. The only time the comb filter comes into play is for analog TV reception or any signal coming in via a composite-video connection. For all other connections, it's out of the loop. In any case, the comb filters in flat-panel TV sets are routinely very good these days.