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Though 1080p resolution has been a feature of some flat-panel LCDs and a few high-end LCoS (liquid crystal on silicon) big-screen sets, this is the first year it will be widely available in relatively affordable rear-projection HDTVs. That’s because 1080p can now be realized with DLP — Texas Instruments’ popular Digital Light Processing “micromirror” technology. The 52-inch Mitsubishi WD-52627 is among the first of a slew of 1080p DLP models coming to market.
I’m a fan of DLP’s picture quality, so I was eager to see how this new Mitsubishi would do, especially since it’s much less expensive than previous big-screen 1080p TVs. At $3,700 list, the WD-52627 brings higher-resolution big screens to ordinary shoppers.
WHAT'S 1080p? Anyone who’s ever shopped for an HDTV has faced the terms 1080i and 720p. These numbers describe the most commonly used HDTV broadcast signals as well as an HDTV’s native display format. Any signal an HDTV sees at its input must be converted to its native format before it can be displayed. The “i” or “p” part describes whether the HDTV displays signals as interlaced or progressive video. More often than not, this depends on the display technology. CRT-based HDTVs, whether direct-view or rear projection, are usually native 1080i — the picture is made up of 1,080 horizontal scan lines flashed up as two fields in rapid succession, each containing half the lines (though in reality, very few displays can produce all 1,080 lines). All fixed-pixel HDTVs — LCD or plasma flat panels, or rear projectors based on LCD, DLP, or LCoS light engines — are progressive-scan displays that flash up all of their horizontal and vertical lines of pixels at once, in the same 1/60 of a second an interlaced display uses to put up one field. But until now, most were limited to 720 horizontal lines of resolution.
Thanks to their bright images and slim profiles, 720p DLP, LCD, and plasma TVs are extremely popular. But the most common broadcast format by far is 1080i. At any moment, these signals carry more than 2 million pixels of information in a 1,920 x 1,080 grid — more than twice as many as 720p. Yet today’s 1080i and 720p HDTVs can’t get them all onscreen at the same time. The TVs simply don’t have enough pixels or produce enough scan lines to do the job. So they convert the signal, essentially throwing out resolution.
Here’s where 1080p comes in. Done properly, it has two key advantages over lower-resolution HDTVs. First, depending on the technology used, the pixels in a 1080p TV will likely be either packed more closely (as with a typical square-pixel grid) or have overlapping footprints onscreen (as in the new DLP technology). That can vastly reduce or eliminate visible gaps between the pixels — the so-called “screen-door effect” — creating a smoother, more natural picture.
Second, when you see “1080p” describing an HDTV, it means the set’s imaging element can theoretically display all 2 million of those pixels in a 1080i signal at once (or the visual equivalent). And since 1080i converts more cleanly to 1080p than to 720p, it’s easier to preserve all that original picture detail. To be sure, going from a 720p to a 1080p display is an evolutionary step — nothing like the upgrade from standard to high-def TV. But the technology has the potential to finally let HDTV be all it can be.
Virtually all the major TV makers are jumping on the 1080p bandwagon. Along with Mitsubishi, Samsung, Toshiba, and even HP are releasing sets based on a new micromirror DLP chip from Texas Instruments, though it’s one that doesn’t actually have the 2 million-plus discrete pixels required for 1080p. A clever technique nicknamed “wobulation” is used to achieve apparent 1080p performance with only half the number of mirrors that would otherwise be required (see “Pixel Magic”). Meanwhile, JVC and Hitachi have 1080p LCoS-based models, Sony is expected to announce new 1080p LCoS sets, and LCD makers will likely follow suit.
It’s only natural that the emergence of 1080p TVs would spawn talk of full-on 1080p broadcasts, which would show us those 2 million pixels at twice the frame rate of a 1080i signal. But 1080p would hog twice as much broadcast bandwidth as 1080i or 720p signals, and broadcasters are already pressed to deliver that much. I’d expect 1080p programming to first be available on next-generation Blu-ray Discs or HD DVDs (though neither camp has announced any plans yet for 1080p). In any event, most of the 1080p HDTVs expected this year can’t even accept a 1080p signal via their HDMI or component-video inputs. But the lack of native 1080p source material shouldn’t prevent you from enjoying the benefits of 1080p with regular high-def programs.
SETUP While the WD-52627 is Mitsubishi’s lowest-priced 1080p DLP, it doesn’t hurt for options. It includes more connections than any set in its class, including a pair of HDMI inputs, two FireWire ports and three component-video inputs. And it has Mitsubishi’s NetCommand system, which uses an onscreen interface to control all the gear that can be connected.
A CableCARD slot offers the potential for watching digital cable without an external cable box. Like most other similarly equipped late-model HDTVs, the set includes the TV Guide On Screen program guide to make up for the loss of your cable company’s electronic program guide. Though free, TV Guide is a less-satisfying solution that requires you to manually re-order the channel lineup to match your cable system, and it’s earned a spotty performance record because of its dependence on local cable feeds for program information. Still, if you’re determined to lose the set-top box, it’s better than nothing.
I liked the Mitsubishi’s extensive picture-quality controls. New this year are two picture presets, Bright and Natural, each of which can “remember” your specific adjustments for contrast, brightness, and color temperature for each input (but not color, tint, and sharpness). This is a great feature for tweakers like me who want custom settings for day and night viewing.
The set also allows users to fiddle with the individual levels of six colors, which let me easily optimize the color balance. A video noise-reduction feature is onboard, but it softened the image, so I left it off for critical viewing.
PICTURE QUALITY My first experience of the WD-52627’s home theater performance came courtesy of The Empire Strkes Back from the Star Wars Trilogy on DVD. This is my favorite Star Wars flick, and its restored picture looked stunning. I immediately appreciated the blackness and depth of space as the camera descended toward the ice planet of Hoth. The shadowy corridors of the rebel base evinced natural gradations from light to dark and few traces of noise.
I also saw the hallmarks of excellent color balance in the icy world. Leia’s face showed a subtle flush as she was teased by Han about her wanting him to stay and fight. As Luke lay in the snow, the wound on his face was colored a deep red but his skin tone looked realistic — not oversaturated.
While the Mitsubishi’s color was strong and accurate, the color-wheel system used to produce color in this and all other DLP TVs is generally more problematic than the three-chip system used by LCD and LCoS sets. The spinning wheel occasionally caused faint trails of color, or “rainbows,” along the edges of bright objects. Many viewers don’t notice these trails, but I saw them about as often on the Mitsubishi as on previous DLP sets I’ve tested.
Fine details, on the other hand, looked great. I set my high-end Denon DVD player to upconvert its output to 1080i format, and the WD-52627 rendered intricate parts of the image with all the clarity I could wish for. From the old-school instrumentation in the Snow Speeder cockpit to the myriad domes, ports, panels, and ridges in the hull of an Imperial Star Destroyer passing overhead, Lucas’s imaginings appeared highly realistic.
With a twinge of regret at leaving Lucas’s galaxy, I went far, far away to look at some true high-def sources. My first stop was HDNet, a 1080i network that was showing a Marianne Faithfull concert. I was immediately impressed by the sharpness of the picture — she was wearing a blouse covered with newsprint, and headlines and subheads in smaller type sizes were clearly visible. I could pick out a few misplaced strands of her blonde hair, and again the deep blacks and shadows of the dimly lit club were deep and clear.
My next stop landed on ESPN’s broadcast of the Home Run Derby. As I watched Bobby Abreau knock dinger after dinger over the left-field wall, I basked in the realism of the crowd and the immaculate field. I could read slogans on people’s shirts and caps, discern collective expressions of awe as a homer sailed overhead.
One of the most impressive aspects of the WD-52627’s image qualty in high-def and otherwise was the complete lack of visible pixel structure. An image of bright light streaming in through a window appeared clean and natural, with no trace of the pixel grid. Even with my nose right up to the screen, it was nearly impossible to detect any pixels at all. If you like to sit close to the screen like I do, 1080p DLP makes a big difference.
1080p VS. 720p I was curious to see how 1080p stacked up against its predecessor, so I compared the WD-52627 side by side with a 50-inch 720p DLP set we had on hand. After adjusting the two for optimum image quality and similar brightness, I fed them the same sources via an HDMI distribution amplifier.
Watching the Marianne Faithfull concert, at first I found it difficult to see any difference in sharpness. Certain edges appeared just a bit sharper on the Mitsubishi, though it was extremely close. But on a Discovery HD airing of The Science of Lance Armstrong, the difference was more obvious. The tiny words used in a computer illustration of a bike were clearly sharper on the 1080p screen. Stubble-covered heads and faces, finely woven mesh shoes, and even the glitter under the paint on the bike frames were extremely sharp on the Mitsubishi and somewhat less so on the 720p TV. Another Discovery Channel show, about the FA-18 fighter, included a close-up of a dummy bomb assembly with tiny words of “warning” whose edges were more distinct on the 1080p display.
Across the board, though, the difference wasn’t dramatic and often depended on program material — less critical viewers would have to look hard to see it even in side-by-side comparisons. It was definitely there, however, and was evident in resolution test patterns, which showed noticably more detail than on any 720p DLP set I’ve tested. The Mitsubishi still fell short of fully resolving a 1080i signal, but I expected that. The screens in all rear-projection HDTVs enhance brightness but sacrifice some resolution to do it, and a 52-inch screen just won’t allow the full potential of the chip to shine through. I expect larger 1080p DLP sets to perform much better on this test.
On another note, I did notice an occasional bit of instability in the Mitsubishi’s picture. In one instance, during the Lance Armstrong episode, as the camera slowly zoomed toward someone onscreen, the glare from a black picture frame in the background undulated slightly. Similar effects occurred with test patterns using 1080i sources, and I suspect they were related to wobulation. But they weren’t seriously distracting, and the picture overall was rock-solid the vast majority of the time.
Video enthusiasts will find 1080p a compelling upgrade, and the lack of visible pixels alone is enough to recommend the Mitsubishi WD-52627 over a similar-size 720p DLP or LCD television. Stepping up to a larger screen size would probably make the higher resolution of 1080p much more apparent. Still, despite being the easiest “sell” on an HDTV’s spec sheet, resolution is only one part of image quality. Factors like depth of black and accurate color play a larger role. Combine the WD-52627’s higher resolution with its all-around topnotch picture, and you’ve really got a powerful package.
Pixel Magic: How TI Puts the 1080p in DLP
Digital Light Processing (DLP) is today’s most-popular fixed-pixel, or “microdisplay,” rear-projection technology. It relies on a chip — called a DMD, or Digital Micromirror Device — that’s covered with microscopic mirrors, each representing one pixel of light on the screen. But rather than try to mass-produce a chip with all 2 million-plus mirrors needed to create a 1080p image, DLP developer Texas Instruments took a different route.
Using an HP technique known as “wobulation” (TI calls it SmoothPicture), TI achieves a 1,920 x 1,080 effective pixel resolution using half that number of mirrors. Wobulation relies on the same principle as interlacing, which shows half the picture at a time, but so rapidly the eye combines the two parts into one. Starting with the square pixel design of its 720p DLP chips, TI turned each mirror 45° relative to the sides of the display, creating rows of diamond-shaped pixels. There are only 960 x 1,080 micromirrors on the grid, but each of them, in effect, creates two separate pixels, one after the other.
During operation, light from the lamp bounces from the chip to a device called an optical actuator, a reflective panel that pivots. In its first position, the actuator reflects half of the image information (the odd-numbered pixels) onto the screen. After 8 milliseconds, the actuator switches position — or “wobulates” — half a pixel-width. Simultaneously, the chip flashes up the picture information for the other half of the image (the even-numbered pixels). This process is so quick that it’s impossible to differentiate between the sets of pixels, and the entire frame, with all 1,920 x 1,080 pixels, is “constructed” within the standard 1/60-second field time. —D.K.
TEST BENCH FOR WEB
David Katzmaier
Color temperature (Low color temperature and Natural mode before/after calibration)
Low window (20-IRE): 5,779/6,457 K
High window (80-IRE): 5,848/6,439 K
Brightness (100-IRE window before/after calibration): 136/43.1 ftL
The Natural picture preset on the WD-52627 automatically engages the Low color-temperature mode, which measured consistently lower (redder) — an average of about 670 K lower than the standard of 6,500 Kelvin. The grayscale remained extremely consistent after calibration at all light levels, varying by only 45 K from the ideal. (Calibration needs to be performed by a qualified technician, so discuss it with your dealer before purchase, or call the Imaging Science Foundation at 561-997-9073.)
Like most DLP televisions, the WD-52627 was extremely bright out of the box, and even the Natural setting comes with contrast set at maximum. I tamed it for critical viewing in the dark, which made the image bearable. The set reproduced the full range of black to white via all of its inputs, including HDMI. Color decoding out of the box was good, with a 5% bias in red and a –5% bias in green according to the color-decoder check from the Sencore VP403 HDTV signal generator, but after adjustment it was close to dead-on. Brightness uniformity was good, with minor hot-spotting toward the middle of the screen.
Convergence was excellent and overscan negligible at an average of 2%, although my review sample did exhibit some anomalies in geometry. The upper-left corner of the screen bowed outward slightly — an effect visible primarily on test patterns and something Mitsubishi warned was a symptom of our early sample. I also saw very slight pincushioning along the right and left edges of images, which was most noticeable when watching 4:3 material.
Black-level retention was relatively good; the level of black remained consistent in all but the most demanding test patterns from the Avia DVD. Even with sharpness properly adjusted, some edge enhancement was visible, which showed up as faint halos around onscreen objects, but this was difficult to spot without test patterns. Sharpness also had a major effect on resolution and high-frequency video noise. I settled on a sharpness setting of 3, with noise reduction set to standard.
The set was unable to accept a 720p signal via its HDMI input, although the component-video input did work with 720p. This was said to be another abberation of our early sample; Mitsubishi indicated the set was spec’d to accept 1080i or 720p (though not 1080p) on the digital inputs and that full production samples should behave properly. Multiburst resolution patterns from the Sencore and the 1080i version of Digital Video Essentials via all inputs revealed that the set could not resolve every detail of 1080i, but the patterns were noticeably more detailed than those on the comparison 720p set. HDMI was noticeably sharper than component video and about the same as FireWire.