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In this report

Demystifying HDTV TV features and specifications

It's no secret that TV sales are in the dumps. Part of that is the economy and part is that thanks to the transition to a digital TV standard, most families have purchased a new TV in the not too distant past. To get those TV owners to upgrade their sets again, manufacturers are cramming more and more technological wizardry into their products, including Internet connectivity to access additional content and the ability to watch certain programming in 3D. Most flagship sets now boast higher-than-high-definition resolutions and some now feature curved screens. Of course, all of this adds to the bottom line of a TV set, but how much of it adds to the viewing experience?

Smart TV

Internet-capable TV has great promise, and many reviewers appreciate being able to stream movies and other entertainment from services such as Netflix, Amazon Instant, Hulu Plus, Vudu, Pandora and many more. Some companies also offer some type of mobile-phone-like app store, with Samsung's being the most advanced in that respect, according to reviews. Many so-called Smart TVs also include at least rudimentary web browsing capabilities, Skype compatibility (sometimes including a built-in webcam), and other bells and whistles.

Entering text, scrolling through menus, and making on-screen selections can be a real pain with a standard remote control, so many higher-end sets come with augmented remotes with full QWERTY keyboards and/or some type of pointing technology to make navigation easier. The most advanced sets also incorporate some type of voice or gesture controls, but the success -- and usefulness -- of those varies. Built-in Wi-Fi is commonplace in all but the very cheapest streaming-enabled sets, so you don't have to worry about having a nearby wired network connection to access all of the online goodies.

Are smart features a must? Maybe not. Reviews indicate that while things have gotten better, many Smart TV interfaces remain a pain to use. Also, streaming content becomes problematic if you have anything other than a broadband Internet connection. Finally, you can get Smart TV features via a host of other devices, including videogame consoles, some TiVo DVRs, stand-alone set-top boxes (such as the Roku), and many Blu-ray players. The bottom line is that while Smart TV can enhance the viewing experience -- especially for those who stream movies and other content from Netflix and similar providers -- it probably shouldn't be the primary reason to pick one model of a TV set over another.

3D TV

Despite TV manufacturers' best efforts, 3D hasn't been a rousing success. Most makers continue to offer 3D, but many have reduced the number of sets with that feature. Vizio, a maker of popular value-priced LED TVs, has announced that 3D will not be offered on any of its 2014 models. That said, a good amount of content is available on-demand from many cable and satellite providers, as well as on 3D Blu-ray Discs.

Two different 3D technologies are available. Active shutter uses glasses that sync to the TV, with lenses that block and pass light in rapid succession to create an image that the brain perceives as 3D in full 1080P resolution. Issues like crosstalk (which appears as ghosting to the viewer) that plagued early active shutter 3D sets have been reduced but not completely eliminated. Active 3D glasses have become significantly lighter and cheaper than in early generation sets, and some have switched to a different syncing technology (RF) that no longer requires viewers to keep their eyes on the picture at all times to maintain the 3D effect.

Some LED TVs offer passive 3D technology instead. The chief drawback to passive 3D is that it cuts the resolution of the 3D image in half, which bothers purists more than typical viewers, surveys find. The pluses are reduced ghosting compared to active-shutter sets, and glasses that are still cheaper and lighter in weight.

Glasses-free 3D TV remains under development, but for now is still something largely reserved for technology demonstrations and trade show floors. No current commercial set includes it, and earlier efforts were very disappointing, and very expensive. Still, experts say that glasses-free 3D technology (also known as auto-stereoscopic technology) is a must if 3D is ever to enjoy wide adoption, but when or if we will see a viable consumer set that includes it remains an open question.

Enhanced refresh rate

When shopping for a TV, you've probably noticed that manufacturers often tout models with higher refresh rates such as 120 Hz and 240 Hz. This refers to how often a TV image is repainted on the screen. Up until a few years ago, all TVs used a refresh rate of 60 Hz, which means the image is repainted on the screen 60 times per second. That's fast enough so the eye sees one fluid, moving image rather than a string of individual frames.

Boosting the refresh rate to 120 Hz or 240 Hz updates the image two or four times more often. What's the advantage? Not much if you're talking about plasma or OLED TVs, and marketing materials that refer to refresh rates in such sets can be safely ignored. However, LCD TVs have traditionally been criticized for being prone to motion blur, which is caused by LCD's slower natural response time compared to other technologies. A faster refresh rate in these sets forces the screen to update more often and overrides the slower response times, wiping out motion blur in the process -- or, at least, that's the theory.

Whether a faster refresh rate makes a noticeable difference in reducing motion blur is a matter of some debate. It does appear to sharpen test patterns and certain types of motion in LCD TVs, such as fast-moving text on a crawler. Lots of experts say they see the most improvement moving from 60 Hz to 120 Hz, with the jump to 240 Hz yielding only a little further sharpening.

The issue with enhanced refresh rates became more complicated in recent years when many TV manufacturers began marketing sets with inflated specifications, backed by a little technical sleight of hand. HDGuru.com's Gary Merson spilled the beans on this. Some reviewers, such as CNET, report a TV's true refresh rate in addition to the manufacturer's claimed specification.

Enhanced refresh rates are sometimes confused with dejudder technology, which is no surprise since the two are often interlocked. Dejudder refers to eliminating a subtle shaking artifact -- called judder -- in content originally recorded on film. While some find judder objectionable, it's what gives film-based video its distinctive "movie" look. Remove judder, and the content looks like it was shot directly to video. Some love the look of the smoother motion but others hate it, calling it a "soap-opera effect," or something a bit less polite. TV manufacturers market dejudder technology under various names, such as Sony's MotionFlow or Samsung's Motion Plus.

Edge lit or full matrix?

Before 2012, the question LCD TV buyers had to answer was whether they wanted an LED backlight or a standard CCFL (cold-cathode fluorescent lamp) backlight. The use of CCFL technology has now all but disappeared, so the question has become whether buyers want an edge-lit LED design with LEDs located only at the edges of the screen or a full-matrix array, often called direct-lit since each pixel subgroup is lit by its own LED. Each type has its pros and cons.

Sets with full-matrix backlights can be significantly more expensive than ones that are edge lit, but some budget TVs use direct-lit backlights that cut costs by using fewer LEDs. Direct-lit sets are slightly thicker than edge-lit sets and are more prone to an artifact called blooming, in which light appears to leak from bright objects surrounded by a dark background. On the plus side, they often have better uniformity (blacks and/or colors are the same from edge to edge on the screen) and better black levels. Blacks can be deepened still further using a technique called local dimming where groups of LEDs (called zones) are actually turned off in areas that call for pitch black. The more zones an LED TV backlight has, the better the effectiveness of local dimming.

An edge-lit LED backlight is thinner than a direct-lit one and more energy efficient, but these LED TVs struggle more with screen uniformity. Owners tend to complain of edges or corners that are brighter than other parts of the screen, especially in very dark scenes. The issue can vary from set to set, however, and bothers some viewers more than others. Some edge-lit sets use a version of local dimming as well, but effectiveness is more uneven -- helping black levels on some sets, but either having little effect or even harming picture quality on others. Buyers of plasma, OLED and projectors need not worry about the backlight, as none of those technologies use one.

4K TV

4K sets, also known as UHD or Ultra HD, have screens featuring resolutions that are roughly four times that of standard HD sets. When fed with native 4K content, these TVs are capable of incredible picture quality.

That's part of the rub with 4K. Up to now, there has been virtually no native 4K content available. Instead, 4K sets have mainly been up-converting standard HD images to fit their screen resolution. The result can be very nice, but 4K TVs can't reproduce information that's not there in the first place. That's why DVDs up-scaled to high-definition resolutions by a Blu-ray player or HDTV can look very good, but not quite as good as a Blu-ray Disc.

Things are slowly starting to change. Netflix has begun streaming some of its content in 4K, including original series such as House of Cards and popular programs such as Breaking Bad. The Blu-ray Disc Association announced a new specification in September 2014 that will bring 4K Blu-ray players and 4K Blu-ray Discs to market sometime in 2015; certainly in time for that year's holiday buying season.

Curved or flat screens?

If you are in the market for a flagship LED TV, you've no doubt noted that some high-end models now sport a curved screen rather than the traditional flat one. Manufacturers are quick to tout the supposed advantages of this innovation, including a more immersive viewing experience, reduced image distortion, and reduced reflections.

However, while experts agree that the curved screens can make an interesting aesthetic statement, most share the opinion of CNET's David Katzmaier, who calls curved-screen TVs "a flat-out gimmick." Instead they find that there's no appreciable difference in the overall viewing experience, at least not in a set with a 70-inch or smaller screen size. Instead, spend the premium curved screens command on a larger TV say reviewers like Katzmaier, James Willcox of ConsumerReports.org, and others. It's a better value for a more immersive viewing experience..

That said, in some situations, curved screens can provide some advantages. A curved screen can miss some of the light sources in a room, therefore producing fewer reflections than a flat screen. However, light placement still will need to be considered as any reflections the screen does produce can be magnified -- stretched over the entire face of the screen in extreme situations. Curved screens also eliminate some of the unavoidable geometric distortions introduced by viewing on a flat screen, but introduce a few of its own related to viewing on a curved surface. Which set of distortions is more bothersome will vary by viewer, so if you are obsessive about such things -- and most viewers never notice them in the first place -- check out a curved screen before committing to one.

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