# HDTV Features Explained: What do you need?



## mechman (Feb 8, 2007)

Modern HDTVs are awash in features, many useful, most not.

We recently covered Meaningful and Meaningless Specs. In this article we’ll discuss the major features one might see while shopping for a new TV: what’s worth spending money on, what’s a gimmick, and what’s actually a detriment to picture quality.

*Plasma or LCD*

While not specifically a “feature” the technology of the television plays a huge part in its overall picture quality. In our testing plasmas produce the best contrast ratios, as in, the ratio between the brightest part of the screen and the darkest. Local Dimming LED LCDs (more on these in a moment) are a close second. LCDs (including LED LCDs) tend to be brighter, and slightly more energy efficient than plasmas. Plasmas are also much cheaper in larger sizes compared to LCDs. I have a pretty comprehensive article called LED LCD vs plasma vs LCD over at CNET with more info on this.

*LED*

LED is still a big selling point from all the major TV manufacturers. There is no such thing as an “LED TV.” The Light Emitting Diodes that create the light that allows you to see an image on an LCD TV are merely a feature. Less expensive LCDs use CCFLs for their backlighting. LED backlight is a feature, and one that doesn’t mean better picture quality. It does, pretty consistently, mean higher prices. LED TVs do tend to be the brightest TVs available, but we can’t imagine a situation where you’d need that much light output in a normal home. LED LCDs are also the most energy efficient TVs, but this is by a tiny margin over CCFL LCD and even plasma. You’ll never recoup the money you spent on an LED LCD in energy usage. If your goal is just to be as green as possible, though, go for it.

*Edgelighting, Backlighting and Local Dimming*

Going along with LED is edgelighting versus backlighting. This is where the physical LEDs are located. With edgelighting, by far the more common of the two, the LEDs are arrayed along the edges of the screen. Depending on the TV, they could be on the sides, the top and bottom, and in at least one case, just along the bottom. Edge-lit LED LCDs tend to have terrible uniformity, so a black screen will have splotches of brighter areas.

Backlighting, specifically local dimming back-lit, will likely be the best picture quality you can get in an LED LCD. Beware! “Local dimming” itself is a feature, and is a description used rather loosely by most major manufacturers. Edge-lit LCDs will often claim to be “local dimming” when in fact only large areas of the screen can be dimmed. This is a far cry from a real local dimming LCD. Only the highest-end LED LCDs at this point have true local dimming.

*Dynamic Contrast Ratio Enhancements*

All contrast ratio specs are lies. None have any basis in truth. Don’t compare them, they’re useless. Any feature purporting to “improve” contrast ratios (other than true local dimming) is also likely bunk. These can be called something like Dynamic Backlight. At best they improve dynamic contrast ratio (how dark a dark scene is, compared to how bright a bright scene), but none improve native contrast ratio (as mentioned earlier, the brightest part of a single image compared to the darkest part of the same image. At worst, they can be detrimental to an accurate image.

*120 Hz / 240 Hz*

All LCDs suffer from motion blur, or a blurring of the image when there’s motion. As a way to combat this, LCD manufacturers increased the “framerate” of the television, or how many images per second flash on the screen. 120 Hz came first, a doubling of the standard 60 Hz rate of plasmas, “regular” LCDs, and older CRTs. 240 Hz and higher are common now. 120 and definitely 240 Hz do improve motion resolution.

However, like “local dimming,” “120 Hz” and “240 Hz” have been corrupted by the TV manufacturers. So much so, it’s hard to tell if the TV is truly more than 60 Hz. One of the ways manufacturers justify calling something a higher framerate than it is (and this includes all 480 Hz or higher models), is by flashing the LED lighting. Take a 240 Hz TV, flash the backlight twice with each frame, POW! you have a “480 Hz” TV. Flash a 60 Hz TV’s edgelighting, or scan it from top to bottom quickly, and you can claim it’s “120 Hz.”

There is no easy way to find out if a TV you’re considering is a “real” 120 or 240 Hz. Sometimes the manufacturer will say, other times they won’t. Usually reviews will list the reality.

This is also a good place to discuss “600 Hz” plasmas. Plasma TVs don’t suffer from motion blur. However, they do suffer from marketing pressures. Facing the avalanche of 120 and 240 Hz LCDs, plasma manufacturers started touting their TVs as 600 Hz. This is technically true, as each frame of video (60 Hz) is made up of 10 sub-fields (60×10=600). However, unlike 120 and 240 Hz (at least the real versions), the sub-fields aren’t a higher framerate. In other words, pretty much all plasmas are 600 Hz, that’s just how they work.

*Smart vs Stupid*

“Smart TVs,” or TVs that have access to the Internet, are all the rage. They give you access to streaming video services like Netflix and Amazon Instant Video. While these are excellent features, their value is dubious, at least in a television. Digital video streamers offer a wider variety of streaming services (including iTunes in the case of the Apple TV), and don’t lock you into the ecosystem of a TV manufacturer. Roku and Apple tend to do a better job with the streaming features, and do so with inexpensive tiny boxes. Generally, if you’re looking for a mid- to high-end TV, they’ll have smart TV features built in. If you’re not sure what you want to spend on a TV, don’t consider Smart TV as a vital feature.


Source: HDGuru


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