Many people are interested in making the jump to HDTV at this time, and with good reason. HDTVs are more affordable than ever, and there is an increasing amount of material available. New shows are avaialble in HD on a regular basis, and now gaming machines (Microsoft’s X-Box 360 and Sony’s Playstation 3) and movie formats (Blu-Ray and HD-DVD) have jumped into the frey as well. One common challenge is the wide range of types of HDTVs available. Which is the best format to buy? Here’s my take on it.
Resolutions: High definition means a finer level of detail than is present in standard televisions. Resolution is measured in the number of pixels (or small dots) that make up the image. The higher the number of pixels, the greater the resolution, and the sharper the image. Typically, TV resolutions are named for their vertical resolution. Standard definition usually refers to 480 vertical pixels. Standard TV is “interlaced”, meaning that instead of drawing the whole picture all at once, it draws the even numbered rows first, then the odd numbered rows next, and keeps going back and forth. If it does this fast enough, you can’t really tell, and it is more efficient because only half the screen is updated at a time. Unfortunately, you probably CAN tell, at least to a small degree when there is motion on the screen. Motion doesn’t look quite as smooth when the image is interlaced. Some technologies (like DVD and some HDTV formats) get around this problem by just updating the whole screen at once instead of doing this interlacing nonsense. It’s less efficient, but some people think it’s worth the extra bandwidth to make it happen. When interlacing is not done, the image is called “progressive” (or “progressive scan”). Usually people combine the vertical resolution with a letter indicating whether the image is interlaced or progressive. 480i refers to an interlaced image with 480 vertical pixels. 1080p refers to a progressive image with 1080 vertical pixels.
Regular TV is basically 480i. DVDs are 480p (provided you have a progressive scan player).
All HDTV broadcasts (over the air or cable) are either 720p or 1080i. Why both? Well some would argue that, since 1080 is higher than 720, that 1080i is superior since it has a higher resolution. Others would argue that since 720p is progressive while 1080i is interlaced, images broadcast in 720p will look smoother than their 1080i counterparts. Both arguments have merit, but you really shouldn’t bother yourself too much with this since you can’t control which format the TV stations choose: you just choose the TV.
What about 1080p? This would seem like the best of both worlds. The problem is that 1080p needs to update 1080×1920 pixels with each screen update. That’s a lot of pixels, and eats through bandwidth quickly, so no broadcaster wants to use 1080p. They’d rather offer 2 channels at 1080i with the same bandwidth. The only practical way to get 1080p video right now is to use a new video disc like Blu-Ray or HD-DVD. However, that doesn’t mean 1080p TVs are irrelevant. Read on…
Forget about a couple types of HDTVs right now:
- CRT (tube) TVs: These old-style TVs offer great image quality, but they are heavy, bulky and their size tops out at about 40 inches. It’s not worth the hassle and limitations.
- CRT rear-projection: Few companies even make these behemoths any more. They were cheap ways into the big-screen HDTV world, but steer clear.
- Front projectors – these project the image onto a wall or special screen from the front. It’s just not practical for most people in most room situations. If you’re interested in this, read up on this elsewhere – it’s a totally different type of viewing experience with different requirements.
Now that we’re done with that, we’re left with 3 main categories.
Digital rear projection – These include LCD rear projection, LCOS/D-ILA/SXRD, and DLP. There are pros and cons to each of these technologies but they all basically work the same way. They project light onto a screen from the back. They make the image either by filtering it through a liquid crystal filter (LCD rear projection), reflecting it off of liquid crystal (LCOS/D-ILA/SXRD), or reflecting it off of tiny mirrors (DLP). Digital rear projection systems generally do not have as good an image quality as direct-view screens (LCD and plasma flat-panels), but they are not bad and they can be an inexpensive way to get to a big screen. Sizes of 60 inches or more, which can be ridiculously expensive as flat panels, may be practical for rear projection. Sony’s SXRD line is probably the best of the rear-projectors, but also are more expensive than most brands.
If you don’t get a rear-projeciton system, you’ll be getting a flat panel display. There are basically two types here: LCD and plasma. People debate endlessly as to which is better. Here are the pros and cons:
LCD – LCDs tend to offer higher resolution (most higher-end LCDs are 1080p, still a rarity in the plasma world), and better brightness, better resistance to burn-in (where a static image can become persistent over a long period of time). However, they are generally more expensive than plasma, particualrly if you are getting an screen 42 inches or larger. The two leading manufacturers of LCDs, Sony and Sharp, have both had quality issues with their high-end LCDs. Sony’s Bravia XBR 2 and 3 lines have been reported to have poor quality images when displaying standard definition TV, and have had some issues with uneven brightness. Sharp’s latest Aquos line has been plagued by bands of darkness that can be faintly seen on the display. The LCD image also tends to fade if you view it from an indirect angle, although not by as much as rear-projection TVs. Many say LCDs don’t display motion as smoothly as plasma.
Plasma – Plasmas, traditionally extremely expensive, have come down in price tremendously. A 50″ plasma can be purchased for as little as $2000 at the time this article was written. Plasmas tend to have rich color and deep blacks, which make for images which many find more realistic than those produced by LCDs. Though the issue of burn-in has been greatly reduced, there is still a theoretical risk if a static image is repeatedly displayed for extended periods of time. A more common phenomenon is temporary image retention, where a static image displayed for a several hours (e.g. a network logo or a video game score) might linger in a ghostly form for an hour or two after it should have disappeared. Plasmas generally have lower resolution than LCD’s. Most 50 inch plasmas offer a mid-range 768p resolution instead of the maximum 1080p resolution. Why should you care if nothing is broadcast in 1080p? LCDs can convert 1080i images into 1080p, so should offer more detail when broadcasts are in 1080i format.
So how to decide?
First decide how much money you are willing to spend and what size TV you want. Can you achieve this with a flat panel? If not, then buy a rear-projection or compromise on size or cost. Generally, I would favor going with a flat panel, but if you really need that 70-inch TV, go for it. Remember, smaller TVs always look more detailed at a given resolution, because the same amount of pixels are crammed into a smaller area.
If you’ve decided a flat panel is right for you, you then need to decide about LCD vs. plasma. If you want a TV 40 inches or smaller, go for LCD: plasma’s don’t do well at small sizes. If you want a TV 50 inches or bigger, go for a plasma. LCDs at 50 inches or above are just too expensive right now and have too many quality issues.
If you’re flexible, here are the issues to consider. First of all, never make your decison based only on how these TVs look in a showroom. Showrooms are generally very brightly lit, which tends to favor LCDs. They tend to feed these TVs with relatively poor quality signals and usually don’t spend the time to optimize the settings for each TV.
LCDs are preferable if:
- You plan on watching TV in a brightly-lit room, where the brightness of the TV is an advantage
- If you plan on spending large amounts of time on a single channel where a logo is displayed in one portion of the screen for a long period of time
- If you plan on using your TV as a computer monitor (where menus, taskbars, etc will be displayed on screen for a long period of time).
- If you plan on spending long periods of time playing a single video game with fixed visual elements
- If you don’t want to stretch standard defniiton TV to fit the widescreen format
Plasmas are preferable if:
- You plan on watching TV in a dimly-lit room, where the rich blacks of plasmas are an advantage
- If you plan on watching a veriety of material on your TV
Overall, I think most people are better served with a plasma, but the differences between these technologies are growing steadily smaller. For those who like the image quality of a plasma but are worried about burn-in, I would suggest buying a plasma from Panasonic, a company whose plasma’s are regarded as being largely relatively resistent to these issues, particularly if you are careful not to display static images or non-widescreen images on the TV for prolonged periods during the first 100 or so hours of TV use.
What about resolution? 1080p is in theory more detailed than 768p supported by most larger plasmas, but to really see a difference, you’ll either need to be sitting too close to your TV or have a TV that’s over 50 inches. Right now, the only affordable 1080p TVs in this size are rear-projection (with the quality drop and bulk associated with this technology). 768p is quite sharp and other characteristics will have a greater impact on image quality.