How To Buy a Flat Screen TV
Be careful!!! Your next TV buy should be selected so that it fits your
home entertainment needs. These include TV, your PC, games and surround
sound music needs. for a careful analysis
Virtually all plasma displays are wide-screen designs, meaning they have a 16:9
ratio of screen width to screen height (also referred to as aspect ratio), which
is the standard for HDTV and very close to the ratio used for most modern
movies. This makes them more rectangular than the traditional, almost square 4:3
displays. With a handful of exceptions, screen sizes start at 42 inches diagonal
and range up to 61 inches.
You get what you pay for in plasma, which means you can't expect to get the same
picture quality from an $1800 42-inch display that you would from a same-size
model selling for $3000. The budget model will most likely be an
enhanced-definition screen rather than high definition and will have poorer
contrast; that translates to a softer picture with less punch and detail.
Even the best plasmas do not quite match the ability of good CRT sets to
reproduce deep blacks and gradations of dark grey. They're close enough now,
however, that you probably wouldn't notice except in a direct comparison. Like
CRTs, plasmas use phosphors to generate light, which means they can be subject
to "burn-in". When a static image is left on the screen for a long time (a
station logo or a text banner, for example), it may not completely disappear
when the image changes.
This is particularly likely to be an issue if you watch a lot of standard TV
programming on a wide-screen display or play a lot of games with static
backgrounds. Fortunately, you can minimize the risk by keeping contrast and
brightness settings reasonable (virtually all TV sets come out of the box with
their contrast, brightness, colour and sharpness controls turned up too high)
and by using stretch modes to fill the screen when you're watching 4:3
programming. In addition, many models now use pixel-shifting strategies, which
continually move the image on the screen in imperceptibly tiny increments to
help prevent burn-in.
Although some plasma displays come with wing speakers that can be attached to
the sides, many are strictly video displays with neither speakers nor any
built-in TV tuner. You will need to factor those additional costs into your
LCD screens range from 15-inch models (or sometimes even smaller ones) designed
primarily as computer monitors up to 65-inch wide-screen designs complete with
speakers and TV tuners. At screen sizes less than 42 inches, wide-screen HDTV
LCDs have become increasingly price-competitive with similar-size direct-view
CRT sets, though, for the most part, they still sell at a premium. A 32-inch
wide-screen display has about the same screen height as a 27-inch TV with a
conventional 4:3 aspect ratio. In screen sizes where LCDs compete directly with
plasmas, the LCDs typically are more expensive, with the gap rising as the
screen size increases.
LCDs have lower contrast ratios than plasmas, primarily because they have a
harder time reproducing deep black and dark grays. Plus, they have slower
response times. They also tend to be one to several inches thicker than plasmas
and have a narrower effective viewing angle. (Plasmas, like CRTs, are easily
viewable from well off to the side and do not exhibit any change in brightness
as you stand up or sit down.) On the other hand, LCDs are completely immune to
burn-in, are easier to view in brightly lit rooms and more often include all the
standard features of a conventional TV.
LCDs also run cooler than plasmas, minimizing the need for
potentially noisy fan cooling. An LCD is a particularly attractive
choice in situations where a plasma would be too large or where you want
a display that can serve double duty as a TV set and computer monitor
Some Technical Information:
What are pixels? Is a wide-screen TV better? We break down the info so you
can make an educated choice about your next TV purchase.
Gone are the days when you figured out how big a screen you wanted, looked
at some sets and bought the one with the best picture that fit your budget.
An options explosion has littered the shopping landscape with numbers,
features and terminology that even experts sometimes have trouble tracking.
So, we've tried to boil the choices down to the basics that can actually do
you some good, and we've noted which are important. (In audio and video,
never forget that just because something has a number to describe it doesn't
mean it really matters!).
We've grouped the specs into three categories:
important, somewhat important, and minor.
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. However, all else is seldom equal. Pumping up the
maximum light output, for example, can increase contrast, but it won't do
anything to overcome poor black level, which tends to be a greater problem
with plasmas and, especially, LCDs. So, take contrast ratings as a rough
guide to be supplemented by eyes-on evaluation. That said, LCDs tend to have
contrast-ratio specs ranging from about 600:1 to more than 1000:1. Plasmas
start at about 1000:1, and many now have contrast ratios of 3000:1 or
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. HDTV is a wide-screen format,
for one thing. 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).
Non-CRT displays, such as plasmas and LCDs, are fixed-pixel arrays, which
means 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, to a somewhat lesser degree,
contrast ratio determine perceived picture detail.
Digital content currently is delivered in one of four formats: 480i, 480p,
720p and 1080i. 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. However, a progressive-scan DVD player
can deinterlace 480i DVDs to create 480p output. 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. When Blu-ray and HD-DVD players come on the market in
2006, they will play discs that actually carry 720p or 1080i video.
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, 1280 by 720, 1366 by 768 and 1024 by 1024 are all examples of
high-definition display resolutions. Small differences are not very
consequential at greater than 1280 by 720, the specified resolution of the
720p high-definition format. Any resolution of 1280 by 720 or greater is
best for viewing high-definition broadcast and DVD content, although, if you
sit close to a large screen, you may prefer one of the new 1920 by 1080
(1080p) displays. Non-HD wide screen is called enhanced-definition; a
typical ED resolution is 852 by 480. Standard-definition, or SD, includes
640 by 480 and 720 by 480. Enhanced-definition displays are best for 480p
content such as that from progressive-scan DVD players.
Important: Video inputs
The number and type of video inputs determine which sources you can use with
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, and most video sources except standard VCRs now have S-Video outputs.
Connection is made with a special cable and multi-pin sockets.
Component video: This high-quality option is the minimum
standard for connecting HDTV tuners and progressive-scan DVD players. It
requires three 75-ohm coaxial cables of the same type used for composite
RGB+H/V: This is another high-quality input type. An analog
red-green-blue horizontal/vertical connection is sometimes used instead of
component video. This input requires five 75-ohm coaxial cables of the same
type used for composite video.
VGA: Video graphics array is a high-quality analog RGB
connection used for computer connections and sometimes in place of RGB+H/V.
DVI: This is one of the highest-quality types of inputs.
Digital visual interface is a digital RGB connection, commonly used for HDTV
tuners and occasionally for DVD players; it may also be used for computer
connections. It requires a special cable and multi-pin sockets. Some
displays with a DVI input may work only with computers, so watch out for
that if you plan to connect an HDTV tuner. Another thing you need for
guaranteed HDTV compatibility is compliance with the HDCP (High-bandwidth
Digital Content Protection) system.
HDMI: Also of the highest quality, High-Definition
Multimedia Interface is basically DVI plus a digital audio link and HDCP. It
can also be mated to DVI with adapter cables. This connection is used on
some HDTV tuners and upconverting DVD players, and it will be the standard
video connector for Blu-ray and HD-DVD players.
Minor: Comb filter type
Comb filters are necessary in analog TV to separate colour 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. Plus, the comb filters in all but budget
CRT TVs are routinely very good these days