Which HDTV Specs Matter? Meaningful and Meaningless Numbers
Shopping for a TV these days involves a barrage of numbers: contrast ratios, refresh rates, viewing angles, and more. Quite often, these numbers are meaningless, and offer little value to the consumer. In some cases, the specs may offer some benefit, but are impossible to compare across different brands.
This guide will help you sort through the marketing gimmicks and focus on what really matters.
Contrast ratio: Meaningless
While contrast ratio itself (the difference between the brightest part of the image and darkest) is the most important aspect of the overall picture quality of a TV, the numbers supplied by manufacturers are completely useless. For one, there is no standard way to measure contrast ratio, so companies often just make up numbers to suit the marketing department’s purposes.
Worse still, you can’t judge contrast ratio in a store. The harsh lighting of most retailers masks true contrast ratio. So a cheap LCD in a store may seem better looking than the plasma right next to it, when, in fact, at home the opposite would be true.
Refresh Rate: Meaningful, but becoming meaningless
LCDs suffer from motion blur, which means that objects on-screen seem to blur when they’re in motion. This can be as obvious as a sportsball person blurring as he runs across the screen, or as subtle as a closeup of a face, blurring slightly as it moves around a little.
The most common way of minimizing motion blur is to increase the refresh rate. This means more images on screen per second than a “regular” LCD. You’ll see these numbers in multiples of 60 (like 120 Hz, 240 Hz, and so on). With video-based content, like sports) these higher refresh rates do indeed decrease motion blur. The TV creates new frames to go in between the actual frames of video. With a 120 Hz TV, it creates a new frame for every original frame in the source. With a 240 Hz TV, it creates 3 new frames.
With film-based content (nearly all movies, most TV shows), however, increasing the framerate causes a noticeable artifact, colloquially called the “soap opera effect.” The smoothing of the motion caused by increasing the framerate causes movies to have an ultra-smooth look that makes them look like soap operas. Many find this to be objectionable (myself included).
Where the term starts to become meaningless, is in the constant effort to “one-up” the competition, companies are starting to market 480, 960, and even higher “refresh rates.” These are always done by some clever math and a flashing backlight. In other words, the backlight of the LCD flashes at some rate, increasing the apparent refresh. Flash it twice with every frame of a 240 Hz TV, now it’s 480 Hz! Using this as the example, some companies call this 480 Hz, while others come up with some clever marketing name for it. Will your eye see any difference between 240 Hz and 480 “Hz” using a flashing backlight? Probably not, though the latter will likely be somewhat dimmer.
Look for “true” or “real” 240 Hz models, if you’re interested. The other technologies are largely specsmanship.
For those who want to nitpick, when I say “film-based” I mean 24 frames per second, which is a frame rate option on modern video cameras.
Plasmas, because of how they work, don’t suffer from motion blur and don’t need higher refresh rates.
Color anything: Meaningless
Pretty much any claim about color is meaningless. All current TV technologies are able to reproduce all the colors supplied on Blu-ray, DVD, and every cable channel. Any additional color is created by the TV is not accurate. You may prefer over saturated colors, but we at HD Guru think a TV should accurately display what’s in the source, not create something on its own. To that end, TVs with adjustable color points or color settings are idea (most mid- and high-end models have this feature).
Viewing Angle: Meaningless
LCD companies like to claim their TVs are viewable at wide angles, with many claiming “178-degree viewing” or similar. This is almost always nonsense. In most cases, yes, an image can be seen at these angles, but the contrast ratio and color accuracy is radically different than what you see straight on (also called “on axis).
The fact of the matter is, only plasma TVs offer a wide viewing angle, with the same quality of image off axis. The next best is IPS-based LCDs, which offer similar viewing angles to plasma, but have historically had a penalty in contrast ratio and black level on axis compared to other LCD technologies.
If you have a large couch, or viewing positions (i.e. “chairs”) that are at an angle to the TV, most LCDs aren’t for you.
TV depth: Meaningless (though read the fine print)
Many TVs are coming out that claim “under 1-inch” of depth. This is sort of true. Part of the TV is likely less than one inch, but not all of it. Most ultra-thin TVs have a bulge at the bottom. In some extreme cases, the TV is so thin that important parts of the TV are in a separate box. This may or may not work for you, depending on how you want to install the TV.
Like anything, read the fine print of the TV’s specs.
Energy consumption: Meaningful
Last year we saw new regulations go into effect that requires TV manufacturers to measure and publish the energy consumption for their TVs. This is, without question, absolutely fantastic. Interestingly, the claimed energy consumption superiority of LED LCDs has been largely marketing hype. While it’s true that the average LED LCD is more efficient than a comparably sized plasma, it isn’t significant enough to offset LED’s higher price.
In other words, if you’re buying an LED to save money, it will take years to recoup the price premium you paid over buying a plasma. If, however, your goal is just to be as green as possible, then absolutely get an LED LCD. Just be sure turn down the backlight.
All CCFL LCDs contain mercury, making them a poor choice if green is your goal.
So what specs do matter?
Here’s the part that’s annoying. There are certain specs that matter a great deal, but you’ll never see them supplied by a manufacturer. These numbers, if reliably measured, would tell you almost everything you’d need to know about a television. In order, they are:
Black Level (minimum luminance level)
Brightness (maximum luminance level)
Accuracy of Color and color temperature
Actual viewing angle (what angle do you lose brightness and color accuracy)
Audio (actual volume potential, without distortion)
It’s worth nothing that while they don’t publish their actual specifications, THX Certified TVs have to meet minimum requirements for color and color temperature accuracy and other specifics.
These numbers, if supplied, plus more subjective factors like video processing performance, would make it easy to judge one TV from another. Too bad manufacturers will never publish specs like this. Why would they? It would be too easy to see what TV was “best.” Fortunately, the better TV review websites (ahem, like this one) do publish these numbers.
And if that’s not gratuitous self promotion, I don’t know what is. Speaking of which, have you seen my book…
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