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Translating TV-marketing

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Translating TV-marketing

by Elmar Salmutter on 04/23/2009

Which specifications genuinely matter, and which ones are just marketing spiel? We take off the rose-tinted specs and get to the bottom of technical data, including brightness, resolution, and contrast ratio.

Translating TV-marketing

Off with the rose-tinted glasses - we give you the facts!

For thousands of years, philosophers have debated the difference between true and false. The result: highly subjective, to this day. You'd think that technical specifications of electronic devices would be objective and reproducible, and you'd be right - in theory.

In practice, however, TV manufacturers constantly try to outdo each other's values in their marketing and brochures. Often, the resulting dream-values - these never-before-seen, record-breaking performances - have nothing to do with the quality of the picture. The fact remains: A Citroën 2CV with wheels will beat any Porsche without. And specified values that the human eye cannot even perceive are irrelevant in the home-theater.

Here you'll find out how manufacturers really derive the values in brochures and spec sheets. Some values are less prone to exaggeration, while others are popular sources of meddling. We give you an overview from A to Z.

Bigger, faster, stronger

Bigger, faster, stronger: Don't believe everything the TV manufacturers tell you.

Technical Specifications Explained

Angle:

The quoted figures for viewing angle are frequently way off the mark. One rarely finds specified values of less than 178 degrees, which would mean the viewer be able to see the picture if they moved one degree in from the side of the TV. This is, of course, nonsense, and viewing-angle dependence continues to pose a problem with LCD TVs. In our measurements laboratory, we repeatedly observe a significant drop in brightness at a viewing angle of 60 degrees.

While it's rare, in practice, to watch a TV from such an angle, there are other associated problems: Besides the reduction in light output, side-on viewing also causes an increase in black level, meaning the contrast also degrades. Colors shift, too - from the side, the image looks less vivid than it does from the center. You can therefore safely ignore the viewing angles quoted in brochures. Instead, base your decision on the details in our independent reviews.

Rear projectors lose much of their brightness and contrast when viewed at an angle - the same goes for LCD TVs.

Brightness of Screens:

In theory, at least, this factor carries a lot of weight. The light output of a screen can be compared with the horsepower rating of a car. Light output is quoted in candelas per square meter (cd/m2) or, occasionally, using the American name for the same unit, "nits".

Candelas, or nits, are defined per area, and can therefore be compared for screens of any size. A 32-inch screen will therefore deliver the same light output as a 32-inch section of a 50-inch screen, so long as the two screens have the same cd/m2 value.

The problem with this value arises from the measurement technique. You can, for example, quote the highest value that's possible to measure. Or you can measure the value at various points on a full-screen, white picture, and determine an average. It's not clearly defined whether the screen should be completely white or only white in one area, and there's also no defined color-temperature at which to carry out the measurement. Still, the exact brightness of LCD TVs is rarely relevant, since the technology always provides sufficient light.

For plasma TVs, too, you can also safely flick past the quoted values - if, that is, the manufacturer even quotes them (Panasonic and Pioneer, for example, no longer do). For plasmas, there are special possibilities to drive up the brightness value, such as by measuring a tiny white spot on a black background, or measuring with the front panel removed - the quoted values are therefore as good as useless for choosing between devices.

A dismantled LCD display - the clearly visible backlight determines basic characteristics of the TV.

Contrast:

This value offers little clarification in the gray world of brochure-science. The maximum contrast value just keeps on growing - in Panasonic's eighth-generation plasmas, it reached (on paper, at least) the 1,000,000:1 mark for the first time.

These values relate to the dynamic contrast, often also known as the On/Off contrast, which expresses the ratio of the screen's maximum brightness to the residual illumination measured for a completely black image. The dynamic contrast therefore gives the maximum-possible peak value, which the TV will, in practice, almost never achieve, and which therefore means very little about the picture quality.

The ANSI contrast is determined using a different measurement technique, based on a checkerboard test-pattern, and offers a more precise indication of quality. Alone, however, it's also not much use.

Based on many years of experience in our AV-measurements lab, we find that a combination of the two values will best represent the actual picture-impression. At Televisions.com, we also measure the In-Picture contrast, which is determined using a small white area on a black background.

Dimensions and Weight:

Almost always correct. What would be the point of quoting a 30-kilo TV as weighing 15 kilos? None! All you'd get is irritated customers and broken wall-brackets.

Gamut:

It has only become the fashion to specify a screen's "color gamut" in the last one or two years. The reason for this is simple: Before then, most flat-panel TVs couldn't fully reproduce the color spaces of TV standards (PAL, NTSC, and HDTV).

It does no harm if a TV can display more colors than the standard defines, but you'll hit problems if the TV cannot reproduce all of the defined colors. We insist on TVs meeting the standard color spaces, at least when in a neutral preset. Otherwise, we're back to the problem of rose-tinted glasses!

The PAL color space represents only a part of the visible colors.

Lifetime of the screen:

Determined based on the reduction in brightness over time. The question remains of which value to take - a reduction to 80-, 50- or 20-percent brightness, for example. With LCDs, the backlight is responsible for the reduction; with plasmas, it's the phosphors that are to blame. It's actually irrelevant whether the screen will last 50,000 or 100,000 hours - other components in the TV will have long given up the ghost by then.

Power Consumption in Watts:

For LCDs, this value is quite realistic; for plasmas, on the other hand, it isn't, and the values vary strongly.

Reaction Time:

The question of reaction times stems from long-past eras of LCD. Liquid-crystal displays used to react slowly to video signals, and weren't always able to switch completely in the time between frames. This resulted in ugly trailing-effects.

By now, however, LCD has all but overcome this problem - the screens have been fast enough for some time. The motion blur still seen on LCD screens results from the nature of the technology itself. 100-hertz technology does tend to make motion appear crisper, but offers no 100-percent guarantee. Plasmas, on the other hand, enjoy freedom from this problem, since they construct every image from scratch. In summary, reaction times haven't been an issue for LCD TV for considerable time, so you can ignore this factor when reading brochures.

Resolution:

The number of pixels never lies. In digital displays, pixels are the smallest picture elements. The higher the number of pixels (or resolution), the sharper, finer, and more detail-rich the picture will generally appear. But the resolution isn't everything - sophisticated video processing can mean, for example, that 1,024 pixels per line might deliver a finer picture than 1,366.

Screen Diagonal:

Watertight -manufacturers never try to pull a fast one here. On flat-panel TVs, the diagonal measurement - quoted in inches or centimeters - refers to the visible screen surface. The casings of CRT TVs obscured some of the glass screen. One inch is equal to 2.54 centimeters.

100 and 200 Hertz:

This is not, in itself, an indicator of quality. The technology has both advantages and disadvantages - and the implementation varies from one manufacturer to another. Ideally, the buyer should refer to test reports and look at the TV in person, in a showroom - then, you can decide for yourself whether the 100-hertz technology brings significant advantages or not.

24p:

24p indicates that a TV can process and play back HDTV signals in 1080/24p - that is, at the current highest resolution, 1080p, and at the movie-theater frame rate of 24 frames per second. The focus of manufacturers and customers alike on this technology means 24p has become a general term for high-definition video pictures in movie quality. But, be careful: The frame rate of the display - 72, 96, or 120 hertz - is also important here, but is rarely quoted. Simply accepting the signals is now something almost all devices can do.

Conclusion

Specified values are no substitute for independent tests. Technical data are only a genuine help if they compare well with test results - only then is it possible to derive useful interpretations. Showing off with supersized values alone says little about the quality of a TV.