Judges in the PC World Labs' image quality tests found that the SV421XVT rendered an acceptable image, but also that it had a hard time displaying fine detail and color often looked inaccurate. Depending on the clip we were watching, we found the image occasionally flat, brownish, too dark, or too orange. I also noticed a lack of detail in black clothing in a nighttime fancy-dress party scene from Chapter 11 of the Blu-ray release of The Dark Knight (a scene that three other people felt was too dark). Another judge noted that the grass in a 1080i football clip looked flat and lacked definition.

But the biggest problems came from digital artifacts--those jumping and scrambled pixels that occur when an HDTV has trouble decoding a signal. Pixelated halos surrounded running players in the 720p baseball and 1080i football clips, and a strange line of garbled distortion ran along the bottom of the screen in the baseball clip (we didn't notice this distortion in any other clips--even the other 720p one, oddly enough). A face looked pixelated in one scene from the Phantom of the Opera DVD, and another had the blotchy, unnatural texture of an oil painting in another scene from that same disc--quite likely problems with the DVD upscaling. In our Blu-ray tests, we noticed slight moiré patterns in a brick wall in Chapter 7 of Mission: Impossible 3, and in a coat's weave in Chapter 9 of The Dark Knight.

The SV421XVT did very well in the panning tests created by the PC World Labs that were specifically designed to test fast refresh rates. It earned 3.5 stars in the horizontal pan test--which is hardly surprising since it's a 240Hz LCD set. But it won an astonishing 4.5 stars in the diagonal pan test--a true torture test designed to push HDTVs to their limit. Yet the brick wall and coat weave problems noted above suggest that there are real-world images it can't quite handle.

There is one visual problem that Vizio could fix with ease if it wanted to: An illuminated Vizio logo right below the center of the screen that glows all the time, whether the TV is on or off (it's dimmer when "off"), and serves only as a needless distraction. This has become a common "feature" in the latest HDTVs, but Vizio is the only company that doesn't provide a way for you to turn off this annoying self-advertisement. I recommend taping cardboard over it--thick cardboard--as a workaround.

An always-on light wastes power 24/7, but in Vizio's defense, it doesn't appear to waste much. According to tests by the PC World Labs, the Energy Star 3.0-compliant SV421XVT burns only a tenth of a watt when off, which is among the lowest levels of the TVs we tested. In use, it burns a reasonable 104 watts (at PC World's standardized configuration).