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Picture This: LCD Market Watch

A display shootout reveals there’s work to be done. 11/01/2008 8:00 AM Eastern

Picture This: LCD Market Watch

Nov 1, 2008 12:00 PM, By Jeff Sauer

A display shootout reveals there’s work to be done.




In an LCD shootout this past September, DisplayMate Technologies and Insight Media compared nine top- and medium-tier LCD models from LG, Samsung, Sharp, and Sony against a CRT studio monitor and a plasma. Photos courtesy of DisplayMate Technologies and Insight Media.

In an LCD shootout this past September, DisplayMate Technologies and Insight Media compared nine top- and medium-tier LCD models from LG, Samsung, Sharp, and Sony against a CRT studio monitor and a plasma. Photos courtesy of DisplayMate Technologies and Insight Media.

Over the last several years, LCD has become the dominant technology for new HDTV purchases. According to DisplaySearch — a market-research firm in Austin, Texas — LCD technology now accounts for more than 80 percent of HDTVs purchased domestically and about 50 percent worldwide. Those numbers include a near monopoly domestically of TVs less than 32in., but also a majority of larger HDTVs.

It's a level of market acceptance that leaves little doubt that LCD technology has reached a more-than-acceptable level of maturity and quality for motion video. Indeed, LCD has greatly improved on many of the drawbacks of previous years and models, such as poor color reproduction, slow refresh rates, motion-image ghosting, and viewing-angle limitations. Yet, even with today's high quality, there is still room for improvement.

Case in point: I was invited to visit the DisplayMate Technologies testing lab this past September during an LCD-panel shootout jointly produced by DisplayMate and industry research and analysis firm Insight Media. The shootout compared nine top- and medium-tier models from each of the four major LCD manufacturers — LG, Samsung, Sharp, and Sony — referencing them against a Sony BVM-series CRT studio monitor and a Panasonic plasma. The focus of testing was on the state of LCD technology as represented by these top makers rather than a particular model's selling features, cabinet design, or price/performance.

Indeed, the specific models tested in this shootout were less important than underlying technologies, such as each company's transfer functions, gamma setup, and ability to produce accurate images. The shootout did include some models with extended color-gamut panels, in-plane switching for a wider viewing angle, and LED backlights that incorporated dynamic local dimming. Testing was performed using a single source distributed to all monitors simultaneously, with test material that included still images from DisplayMate as well as a variety of motion-video content such as fast sports clips, slow camera pans, and other challenging material.

THE BEST OF THE BEST

As you would expect, picture quality from all the LCD panels tested, particularly from the top-of-the-line models, was excellent — at least on the surface. Although there were slight variations — for example, Sharp tends to over-saturate colors in favor of a very bold, if somewhat exaggerated, picture — all LCD color reproduction was at least comparable to that of the CRT and plasma. However, the testing and the testing report revealed some surprises.

For example, LCD's lingering reputation for poor refresh and image ghosting — which is most noticeable on fast-motion sequences such as sports footage — seemed almost moot. In order to combat that lingering perception of poor motion performance, LCD makers have introduced 120Hz panels with double the frame rates and inserted either black frames or synthesized in-between frames using motion estimation. However, the conclusion from the shootout is that the 120Hz units performed essentially the same as the 60Hz units, suggesting that the continuing trend toward 180Hz and 240Hz units may be little more than a marketing spec numbers game.


Picture This: LCD Market Watch

Nov 1, 2008 12:00 PM, By Jeff Sauer

A display shootout reveals there’s work to be done.




The most surprising test results in the LCD shootout were in viewing-angle performance. Pictured above, the same still image is shown on the same LCD screen but from two different viewing angles. On the left, when viewed straight on, the red color is excellent. However, when viewed at roughly 45 degrees in person, the LCD shows a severe color shift as shown on the right.

The most surprising test results in the LCD shootout were in viewing-angle performance. Pictured above, the same still image is shown on the same LCD screen but from two different viewing angles. On the left, when viewed straight on, the red color is excellent. However, when viewed at roughly 45 degrees in person, the LCD shows a severe color shift as shown on the right.

Dynamic LED backlighting yields very dark black levels and very high contrast ratios. This isn't surprising since the LEDs can be physically turned off. However, because the LEDs are clustered and they light regions of the screen rather than individual pixels, the testing report notes that “objectionable halos appear around bright objects that are embedded in dim or dark surroundings.” In other words, there's an inherent trade-off. Personal preference will determine whether the added contrast and black levels outweigh the halo artifacts.

Yet, clearly the most startling test results were in viewing-angle performance. It's a problem that's inherent to the way LCD produces images; that is, by shining light through a pixel grid (as compared to emissive technologies such as CRT and plasma). LCD TVs now regularly boast viewing angles between 170 degrees and 176 degrees. However, that can be misleading, as the shootout showed very overtly.

The image of the barn door on p. 24 shows the same image on the same screen from two different angles. When viewed straight on, the red color is excellent. However, at roughly 45 degrees, the display presents a severe color shift that can be seen in the image on the right. More surprisingly, when viewed in person, that color shift begins to appear outside a much narrower viewing angle; it's literally one step off-axis in either direction from the center. In the image of the young girl on p. 22, a slight move away from center turns a smiling, healthy-looking child into a more ashen-faced, unwell-looking girl as seen in the third LCD from the left. Neither the reference CRT nor the plasma showed any such color shift at wide viewing angles.

Why is this color shift not more visible to the average consumer? First, color shifts are far less noticeable on moving images than still images when one can move and witness a color change firsthand. Second, the specific images chosen by DisplayMate speak directly to thousands of years of human evolution: finding nutritious food to eat and recognizing healthy faces. How red a barn door is will likely pass right by the average viewer without the benefit of side-by-side comparison. And lastly, our eyes are generally not terribly astute about color.

Contrast ratio also suffered greatly in off-axis viewing. Test measurements taken at an angle of 45 degrees were, on average, about one-quarter of the contrast ratios measured straight on. The best 45-degree contrast-ratio performance came from Sony, dropping to roughly one-third the contrast ratio (467:1 at 45 degrees compared to 1344:1 straight on). Interestingly, while the panels with in-plane switching did a better job of maintaining color accuracy at wider angles, they suffered more loss of contrast both straight-on and from wide angles; this suggested another serious trade-off and a reason why the top-tier panels do not include this technology.

There is a lot to like about today's LCD panels and HDTVs. Image quality can be excellent, motion smooth, and colors strong, but DisplayMate and Insight Media have shown that there's still room for improvement as LCD looks to become the standard by which others are judged. The full testing report is available at www.insightmedia.info.


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