Don’t buy an HDTV without reading this first

http://blogs.techrepublic.com.com/Ou/?p=458&tag=nl.e019

• Date: March 31st, 2007
• Blogger: George Ou
• Category: Fun Stuff, Hardware

• Blog Post
• Comments
• Permalink

• Save to my Workspace
• E-mail This
• Print This

Forking out a few thousand dollars or even just a few hundred is a serious investment, and the last thing you want to do is buy an HDTV with lousy color rendition.  Navigating the minefield in consumer electronics is a confusing proposition even for the seasoned gadget geeks, so I created this survival guide to help you make a wise decision.  I'll explain the various types of HDTVs as well as cabling and testing the color depth of your display.

Projection HDTVs:
These typically use DLP, LCOS, or LCD technology (don't confuse LCD in this context with an LCD flat panel display, because this refers to a small LCD chip being used in a projection HDTV). The advantage of projection technology is that it's relatively cheap for a very large HDTV. For example, you can get a 72" projection HDTV that has 1920×1080 resolution from $2500 to $5000 depending on the brand and model.

The disadvantage is that they don't have as good a viewing angle and they're not as bright compared to LCD or Plasma. Sometimes the resolution isn't quite honest because they may advertise "1080p" non-interlaced capability, but you'll be surprised to find that it will only take an interlaced signal via the HDMI or analog component ports. The other problem is that they're often over-scanned, which means the edges will be chopped off. I found out the hard way that even my Windows Start and Task bar were completely chopped off at the edges. I actually had to use some neat driver tricks in my NVIDIA video card to compensate for the over-scanning by telling the driver where the image was being chopped off.  The color depth on projection HDTVs is also lacking compared to the LCD flat panel displays, though the higher end projection models don't trail as badly. Another problem I need to point out is that projection TVs take a lot of power.  My own 72" DLP uses about 250 watts of electricity when I hooked it up to the power meter. The lamps also need to be changed every four years or so, and they cost about $200.

The bottom line is that you get a lot of size for your money when choosing a projection model, but the quality can't compete with the quality of LCD flat panels.  Note that when I say the quality is lacking, that's only in comparison to LCD/Plasma flat panels, but projection is still vastly superior to older HDTV or TV sets. The main advantage of larger displays isn't necessarily because they look bigger; size allows you to place the HDTV farther away from the audience, which means you can have more people viewing it. If you don't mind sitting a little closer to a smaller but higher quality LCD flat panel, it will look just as big but it can't be viewed by as many people and it may not work for larger living rooms, even if there aren't that many viewers.

Plasma HDTVs:
Plasma displays can come in very large sizes equal to projection HDTVs, but they cost a lot more money for a given size. They can easily cost two or more times per inch than an equivalent DLP. A current 65" plasma HDTV that supports 1080p costs anywhere from $6000 to $10000.  The viewing angles, color depth, and brightness on plasma displays are vastly superior to projection displays. You also get true 1920×1080 non-interlaced resolution.

The problem with large plasma is they can cost as much as a cheap automobile and the price is constantly dropping. I wouldn't be surprised if the price dropped 30% next year while the quality goes up. I know people who forked out $10000 two years ago for a smaller 1366×768 resolution plasma, and they're probably kicking themselves now. Unless you just have too much money to burn, I can't recommend a large plasma display. Another word of caution is that there are some really cheap smaller plasma displays that have 1024×768 resolution that might sound like a good deal, but you're getting something that doesn't have square pixels. If you try to hook up a computer to it, it will look ugly and distorted making everything look fat. Any model that has a resolution of 1024×768 or less is obsolete and I would stay away from them.  [Update - I forgot to mention that plasma displays have burn-in problems.  I've seen first hand how bad the burn-in can be within just two years when the displays were used in a datacenter for monitoring mostly static images.  This isn't as serious when used for displaying video, but there can still be problems when there's letterboxing on the sides or top/bottom.]

The bottom line is that you can get a large high-quality plasma display but at very high cost. There are cheaper, smaller versions, but you're better off getting an LCD flat panel HDTV for about the same money and at better quality.

LCD HDTVs:
LCD HDTVs are typically very high quality and very expensive for a given size, but they have recently grown in size and dropped in price. You can easily find 32" LCD models with 1366×768 in the $500 to $800 range. 42" Models with 1920×1080 (1080p) resolution can be $1200 to $2000, while 52" LCD 1080p models go from $2300 to $3500. There are 60-plus inch models that are priced out of this world at even higher prices than plasma displays. Larger models will eventually come down in price but now is not the time for anything over 52". So for the cost of a 72" projection HDTV, you can get a 52" LCD model that has vastly superior image quality with none of the interlacing and over-scan problems.

[Update 4/2/2007 - One of the more interesting developments is the availability of the newest 120 Hz LCD HDTVs that offer frame interpolation. This means that 24-frame-per-second cinema sources can be cleanly multiplied by 5, and NTSC video sources with 30 frames per second can be cleanly multiplied by 4. The interpolation actually means that the display will create three or four additional frames in between each frame to fill in the gaps with an image that's somewhere between the original frames. That creates an extremely smooth and life-like look-and-feel. I can see where this might actually cause some issues with movie footage that deliberately shows a low frame rate for certain artistic effects, so the frame interpolation may undo those effects. The Sharp Aquos LC-46D92U, for example, boasts this kind of 120 Hz frame interpolated operation with a super fast response time of 4 ms and an ultra-wide viewing angle of 176 degrees. The 46" LC-46D92U costs about $2500 (probably a lot more from retail stores), which is on the expensive side. But we can expect the price of these to drop when more of the 120 Hz LCDs become common.]

If you're willing to place the display closer to you, the smaller LCD will look just as big as the projection model, but it will look much better. The quality won't be as good as a high-end 20" computer LCD, but it beats any other HDTV on the market. It's so good that you can even use it as a computer monitor without eye strain. The only word of caution is that the 1366×768 resolution isn't universally supported, and you need to make sure your video card and drivers can support that resolution or else things will look very ugly because of resolution rescaling artifacts. Personally, if I had to do it all over again, I wouldn't have gone for the big cheap projection DLP and gone with the LCD.

ATSC tuners and free HDTV:
All newer HDTVs have built-in ATSC tuners, which means you can get free high definition content over the air. I'm one of those people who don't watch that much television, and I refuse to pay for cable or satellite.  If the HDTV you're looking at purchasing doesn't have an ATSC tuner or it doesn't have HDMI or DVI input ports, skip it. All you need is an outdoor antenna, though indoor models can still allow you to receive most of the digital channels, especially if you live in an area close to the broadcast towers. There's also no such thing as an "HDTV antenna," and any old antenna will work. Reader Zoraster pointed out that HDTV operates in the UHF band, which is all the channels above channel 13. VHF is channels 2-13, but there are some instances where HDTV is broadcast over VHF. If you have an old TV antenna on the roof with all the coax cabling in place, it will work fine if it supports UHF. I bought a $40 outdoor antenna and it brings me about 15 digital channels, many of which are high definition. All the major broadcast networks are available over the air in HD, and even if you intend to pay for cable or satellite, it's still a good idea to have the free HD content over the air so that you don't have to pay for local channels and HD.

Monster cable ripoff:

Consumers need to get the concept of "monster cables" out of their minds since they DO NOT apply to the digital world. There is zero difference in quality between the cheapest $12 HDMI to DVI cable versus the $100 gold-plated "monster cable."  Monster cables are a holdover from the analog era, where signal leakage results in a degraded image or sound. In the digital world, a data cable either works 100% or it doesn't work at all, and there is no degraded middle ground. Since nearly all digital cables work (return the rare ones that don't), there isn't a shred of difference between the cheap cable or the expensive monster cable. If you can't find an HDMI to DVI cable for less than $30 in a retail store, you can google "HDMI to DVI cable" and there will be plenty online vendors selling them for $12-$16 plus shipping. Don't be shocked to find HDMI cables that cost $60 to $150 in a typical retail outlet; just don't fall for it. The only place monster cables have any use is for the transmission of analog signals, such as the connection between your amplifier and your speakers.

How to test the color quality of an HDTV:
Once you decide what kind of HDTV you want to buy (read below), you'll want to test it before you buy it. I was discussing the issue of HDTV quality with colleague Justin James, who was in the process of buying a new LCD HDTV. We discussed how daunting it was to figure out the differences between an expensive and inexpensive model. Making matters worse, the stores usually don't show you an optimal image with the proper digital HDMI high-resolution video source.  Even when a clean digital signal is used, it still isn't easy to judge the quality of an HDTV. HDTVs are often placed in worse glare conditions than others, and the ones the store wants to sell most are often conveniently placed in to more favorable lighting conditions. Another trick is that some HDTVs are set to a very high contrast mode so that the images look vivid and bright, but the reality is that the shadow detail and/or highlight detail is sorely lacking. Even to the trained eye, judging the color depth on a monitor without a color gradient chart is difficult. So I've gone ahead and created some red, green, blue, and gray scale charts optimized for different resolutions for you to download. 

Armed with the color gradient chart and a laptop with high resolution output, Justin James planned to go to the store to check the quality of the HDTVs before committing his hard earned dollars. The downside to that option is that you won't be able to test the digital HDMI or DVI port, and many people may not have a laptop with a good enough graphics card that supports 1366×768 or 1920×1080. Another option is to buy the HDTV from a retailer that lets you take it back with no penalty, though this becomes difficult if the HDTV is extremely large. You can try to get the sales staff to show you as much as possible so that you can make a fairly good decision, but warn them that you will inspect the product at home and return it if it doesn't live up to expectations.

To test your HDTV, download the following image files and display them at full screen. Find the resolution appropriate for the model you're considering.

• For 1080p (1920×1080) resolution models
• For 768p (1366×768) resolution models
• For 720p (1280×720) resolution models
• For computer monitors that are 1680 pixels wide

The idea is that you should ideally be able to see distinct square color blocks from left to right and top to bottom. Realistically, you won't even see all of them, even on a good computer LCD, much less an HDTV. The only thing that will display all of them is a bulky CRT monitor. Computer LCDs can't normally match the color depth of CRTs unless you pay three to four times the cost of a normal LCD display for a very high-end LCD.  With most LCDs, you can tilt them forward and back to see more shades of color at either end of the spectrum, but not without losing color depth at the other end. The real question is how many color tiles can you see when you're at the optimum viewing angle without any adjustment and how many colors and shades can be displayed at once at a given viewing angle. Using these test patterns side by side is the only way most people can tell which display is the better one. Fortunately, with LCDs or plasma displays, you don't really need to worry about screen geometry distortion, so there's no need to do the grid line test.

While there may be some quality difference between more expensive and cheaper LCD models, just keep in mind that the cheapest LCD has higher quality than the best projection model. Assuming it passes the quality test, I personally tend to favor the cheaper LCD models than the more expensive LCD models because I can't see the more expensive models being worth nearly double the price if the cheaper model has the specifications and features I want.