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Fact or Fiction? 8 HDTV Myths Demystified

We sort through eight of the most confounding HD concepts to help you buy with confidence

By Zack Stern, PC World
March 08, 2010 11:12 AM ET

PC World - If you're buying your first HDTV or an upgrade from a starter set, your new television may deliver a better picture than the one you're used to. But picking the right HDTV can be confusing, especially when your favorite blue-shirted salesperson may be steering you in a certain direction in hopes of a bigger commission. Or maybe the rep is just misinformed. Whatever the reasons, the environment has rncouraged a cavalcade of claims about HDTVs--some of which were true for first-generation sets but have little relevance to today's buyers, some of remain valid, and some of which were never true.

I'll highlight some of the most prominent assertions made on the showroom floors of big-box retailers and explain the realities, along with tips and details for buying an HDTV, selecting the best content, hooking up the set at home, and more.

Claim: "HD" signifies a specific standard of quality.

Status: False

Though "HD" does stand for "high definition," HDTVs come in several resolutions; and in any event, a set's resolution doesn't completely determine the exact image quality you'll see on your screen. For one thing, screen sizes vary. Other factors affecting the picture include the transmission--over the air, via cable, by satellite, or from the Internet--and the original source material.

These variables help explain why you can get high-def content from Amazon, Hulu, iTunes, Netflix streaming, a Blu-ray disc, and other sources, and yet encounter wildly different picture quality.

The basis for the real broadcast signal standards is ATSC (Advanced Television Systems Committee), and even that has many options.

If you have an HDTV and a digital tuner, ATSC governs your over-the-air signal. ATSC content may be in either standard-definition (in either 4:3 or 16:9 aspect ratio) or high-definition (16:9 aspect ratio) format, with the resolution varying accordingly. A standard-def transmission consists of 4:3 images transmitted at a resolution of 640 by 480 pixels.

The most familiar of the HD resolutions are 720p (consisting of a 1280-by-720-pixel frame) and 1080i (composed of 1920-by-1080-pixel images). The "p" stands for "progressive scan," meaning that the set creates the image by continuously redrawing the frame, line by line. The "i" stands for "interlaced," meaning that halves of the full frame are shown 60 times per second, but your eyes combine them into a full-frame image reproducing itself at a rate of 30 frames per second. At the same resolution, a progressive-format image looks better than an interlaced image.

Over-the-air broadcast standards top out at 720p and 1080i, but you can obtain the full 1920-by-1080-pixel frame in 1080p from Blu-ray discs, certain Xbox 360 models, and the PlayStation 3 units.

Compression and bit rate are other factors in picture quality. A Blu-ray disc should look better than a cable TV feed of the same content at the same resolution, since the disc has more bandwidth than the cable broadcast.

When choosing for picture quality, remember: 1080p is at the top, 720p and 1080i look similar, and anything below them won't be as good. Keep those terms in mind because they represent official standards, not marketing terms.

Originally published on www.pcworld.com. Click here to read the original story.

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