In particular, we wanted to check one of LG’s most unusual claims: That unlike the Vizio set, LG’s passive 3D TVs were capable of displaying true 1080p (1920x1080) resolution to each eye. That claim goes against our general understanding of the current passive polarization techniques, which typically cut vertical resolution in half. In 3D mode, these passive TVs essentially divide the display screen—and thus the 3D stereo image—into odd and even lines, each group having a different polarization. The matching polarization in the glasses then steers the odd lines to one eye and the even lines to the other eye, which means each eye only sees half the 1080-line vertical resolution (1920x540).
So how can LG claim 1080p resolution when each eye is forever blocked from seeing half the lines? For each single frame of incoming video, LG refreshes the image to each eye two times. For one eye, the first pass presents the odd lines of the 1080p image onto the odd line rows of the screen, followed by the even lines, which are also—and unusually—presented on the screen’s odd line rows (not on the even line rows).
While this method technically presents each eye with all the 1080p information, it does so by placing half the lines of video in the wrong row location, at odds with standard video processing practices. Since the odd and even line information is presented sequentially to each eye, but in the same line locations, at any given time each eye is still only seeing half the resolution. But we’ll reserve final judgment for our resolution tests, which are presented below.
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1080p resolution—really?
We found that despite its claims, the LG LW5600 wasn’t able to produce true 1080p images to each eye in the 3D mode. The loss of resolution was apparent on our resolution test patterns, as well as on regular programming, where we saw course, jagged edges on objects that should have been smooth, and on broken lines that should have appeared continuous. It was especially visible on graphics and text, where we could see scan lines (see photo above). But on natural video (people, nature scenes), the lack of resolution and related artifacts were less apparent and never distracting.
In general, image artifacts caused by the lack of vertical resolution are definitely less pronounced on the LG than on the Vizio, whose jaggies and coarse edges are very prominent on most content. But it didn’t produce the clean, crisp edges we expect from true 1080p images, such as those we’ve seen on the best active 3D sets.
It should be noted again, however, that the ghosting and banding issues we’ve mentioned disappear when the TV is within the appropriate vertical viewing angle and proximity limits of the LG. Our initial evaluation leads us to believe that the LG set has a better overall image quality than the Vizio, thanks to the reduced coarseness in the resolution. But in 3D mode the LG does not provide 1080p resolution, though it may be good enough for all but the most discerning viewers.