The HD Decision

By Colbin Brin

"Buying a television isn't as easy as it used to be," says Matthew Torres, about.com's Guide to TV and Video. "It's like buying a computer. You have features in one you like, then features in another you like." This is particularly true for HD sets, so if you're planning on buying a new one, there are some things you'd be wise to take into account before handing over the plastic. We asked Torres to elucidate the more fundamental attributes of HD TVs, to help you become an educated consumer. And lest you think this is a bit too complicated, don't say we didn't give you fair warning. "At some point, televisions are probably going to be custom made," Torres hypothesizes.

What is the difference between 720p, 720i, 1080p and 1080i? What do these things even mean?

The numbers stand for lines of vertical resolution, while the letter i stands for interlaced scan, and the letter p, progressive scan.

Okay... Come again?

Lines of resolution are important because they determine the level of detail of the image. When you have 720 lines going across the screen horizontally, each one has to be a certain thickness when they're stacked on top of each other, so that they fill the screen. The more lines you have, the thinner they become, the finer the detail. So 1080 displays crisper images than 720.

And the scan?

The scan is the way the TV displays the lines of resolution to form a moving image. One second of video is composed from 30 frames, and two scans equal one frame. In an interlaced scan, the odd lines are displayed in one scan, followed by the even lines in the second scan, to make one frame. In a progressive scan, both scans in the frame contain both even and odd lines, so the image is a bit richer.
HD TVs go up to 1080i or 1080p.

What is the difference between LCD (liquid crystal display) and plasma?

These are different technologies. Plasma TVs use pressurized gas chambers to create the image on the screen; LCD uses liquid crystals. Plasma displays motion and black levels a bit better.

Isn't black black? How could one black be better than another?

Some TVs can produce a true black. Look at the bevel around the screen. Manufacturers will often make it the same shade of black as the black that can be displayed on the screen, so that black appears as dark as possible. But it may not be truly black.

If plasma is better overall, why would anyone ever buy a LCD?

They're each good for different things. Plasma is better for watching TV and movies because motion is better and the contrast and colors are deeper. It also costs less, but it's susceptible to overheating. That's why you need to make sure it has breathing room around it. Plasmas also can suffer from "burn in," which is when an after-image remains on the screen after a still image — a network logo, for example — has been shown. LCD sets are good for playing video games, and since they don't get as hot, they don't require as much breathing room.
LCD sets either have a speed of 60 or 120 hertz. I'd only buy an LCD with a frequency of 120 hertz.

What is HDMI?

HDMI stands for High-Definition Multimedia Interface. It's a type of cable that connects your TV to your other video consoles, such as a DVD player, video game console or computer. HDMI is faster, and its bandwidth is higher, than other component video hookups, including a coaxial cable, S-Video and DVI (Digital Video Interface). If you want a true digital image and sound, buy a TV that supports HDMI and uses HDMI cables.

Would the average person notice the difference between an image coming through a DVI cable, and an image coming through HDMI?

I'd say no. You'd have to have them side by side to notice, and most people don't put two TVs side by side in their homes. I compare it to how some people believe a BMW has a better engine than a Honda. The HDMI is a better cable, but not everyone would notice.
However, your TV should have at least one HDMI hookup because all sorts of components are being outfitted to fit with HDMI going forward — DVD players, game consoles, home theater receivers. Also, HDMI holds video and sound in one cable, so there are fewer cables and wires around.

There's one more acronym we're hearing about. What is HDCP?

HDCP stands for High-bandwidth Digital Content Protection. It's a type of digital copy protection, developed by Intel. From what I've heard, if you're watching something encoded with HDCP and you're not connected through HDMI or DVI, the image will be distorted. It's a copy protection deal.

I don't understand fully.

Neither do I. The bottom line is, the technology is not going to disappear, and it could affect your viewing in the future, so you should buy a set that's DVI/HDCP or HDMI/HDCP compliant.

Let's get to the more intuitive questions. For one, how should I decide how big my HD set should be?

It really depends on the size of the room where it's going.
The Canadian Association of Optometrists recommends that you watch TV from a distance of five times the width of the screen. For instance, you should sit six to seven feet away from a TV that's 16 inches across its base — not its diagonal.
I will say this, though. HD TV's are widescreen, and with a widescreen, you can go a little larger and still be comfortable. So if you're choosing between a 32-inch widescreen and a 37 inch, go with the larger model. It's like shoes for kids. You'll grow into it.

Is there a technical claim that brands make that is not so important?

Don't fixate on the contrast ratio. Manufacturers have a way of manipulating that number; there's no standard measure. It's not a reliable stat.

Do you have any other advice for buyers?

If you're thinking about a particular set, read the product literature on the manufacturer's website. If the literature doesn't mention anything about picture enhancement — how the set enhances older, non-HD movies or images, for example — the TV can't do it.

Visit Matthew Torres at http://tv.about.com

The opinions expressed in this article are not necessarily those of DIRECTV.

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