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| The Vizio SV470XVT had a mixed performance in our blacks & whites tests. Black level was not impressive, but peak brightness was good. The poor black level contributed to less than stellar contrast, but blacks and whites did remain stable when we combined them with the opposite color. We were impressed by the greyscale gamma as it hit our ideal almost exactly. |
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Black Level (4.94) 
How well a display produces black is key to getting a good picture out of your HDTV. The Vizio SV470XVT's deepest black was measured at 0.41 candelas per meter squared (cd/m2). This is not very impressive. LCD televisions like the Vizio SV470XVT sometimes struggle with black level due to the fact that the backlight on the TV is always on, so some light will always escape. Even for an LCD TV, however, we've seen significantly better black performance from other televisions like the the 46-inch Samsung LN46A750. Compared to Plasma televisions, which do much better on black level because they have no back lights, the Vizio SV470XVT's performance is even less impressive.
Peak Brightness (9.09)
Peak brightness is the opposite of black level, this tells us how bright the brightest white gets. We measured Vizio SV470XVT's peak brightness at 374.93 cd/m2. This is quite reasonable and should be plenty bright for most viewers. We were pleased to see this level of brightness even after we turned down the Vizio SV470XVT's contrast significantly to ensure we got sufficient detail in the display. If you absolutely need more brightness you can turn the contrast up, but note that you will lost significant detail at the high end of color accuracy. We calibrate for maximum detail rather than maximum brightness.
Contrast (5.89)
Contrast is the ration between the blackest black and the brightest white. The Vizio SV470XVT's contrast was measured at 914:1. This is not as impressive as we've seen from some other displays, mostly due to the lackluster black level we saw from this display. It is in line with what we saw form the Vizio VO47L, but nowhere near as good as the Samsung LN46A750. You should also note that this is significantly worse than the 6500:1 contrast ratio quoted by Vizio. This is because manufacturers turn the backlight on their display as low as possible to get a black level that most users will never see. We do our test with the black level turned up to maximum, which is where most viewers will want it.
Tunnel Contrast (8.63)
Of course most scenes you'll view on your HDTV aren't going to be purely black or white, instead scenes will have gradiations of both. As such we test tunnel contrast, which tells us how well blacks hold up as the amount of white on the display increases steadily. Below you can see a graph of black level as the percentage of white increases.
Almost all displays increase in brightness a little, but we were pleased to see that the increase on the Vizio SV470XVT was quite minimal with black level varying from 0.41 cd/m2 on an all-black display to 0.58 cd/m2 on a 95% white display. You can see on the graph that this variation is minimal.
White Falloff (9.79)
This test is the opposite of our tunnel contrast test, so we look at how well whites hold up while the percentage of black on the display increases. The Vizio SV470XVT did very well in this test with almost no change in white level even when 95% of the display is black. You can see this in the graph below as the line indicating white level stays almost completely level as the prcentage of white on the display is steadily decreased.
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Uniformity (8.13)
In this test we look at how smooth and uniform blacks and white are on the display. The Vizio SV470XVT did well in this test, with only minor issues. In particular we noted that when the display was all black the corners were slightly brighter than they should be and there was a small patch on the left edge of the display that was also noticeably brighter. On the all white display issues were even less pronounced, with only a small amount of darkening along the edges and in the corner. We detected no banding or major blotches in the middle of the display, which would indicate a major problem.
Greyscale Gamma (8.44)
Update: We have rescaled our scoring for this section. The original score was 10.0.
Greyscale gamma refers to the shape of the curve as the display goes from black to white. The Vizio SV470XVT did exceptionally well in this test. Below you can see the graph of the Vizio SV470XVT's greyscale gamma curve. We plot the curve exponentially because the human eye works on ratios, not specific levels, so the luminance increases exponentially. Ideally a television would have a gamma between 2.4 and 2.5. The Vizio SV470XVT nailed this by posting a gamma of 2.46, right where we want it.
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To make this a bit easier to understand we use a logarithmic scale to plot the curve along a straight line, which you can see above. The blue line represents our ideal, we want as little deviation from this line by the lack curve representing the Vizio SV470XVT's performance. You can see that the Vizio SV470XVT matches the line almost perfectly. What this means in practice is that the television will make adjustments between white and black in smoothly and accurately, without any sudden jumps, which could cause problems such as banding or lack of detail in subtle changes in brightness. The original curve can be seen below.
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Resolution Scaling (7.78)
The Vizio SV470XVT is capable of displaying a full 1080p HD signal. The reality is, however, that the only way you're going to get a 1080p signal is by hooking your TV up to a Blu-Ray player, so it's important to see how televisions handle other signals. As such we run a 480p, 720p and 1080i signal through the Vizio SV470XVT to see how well it handled them.
480p (7.83)
480p signals are what you will get from standard defnition TV or DVDs. With the Vizio SV470XVT we noticed few problems with legibility and resolution, items were clear on the screen with no moire patterns and only the smallest font sizes will be difficult to read. Where we noticed more of a problem is with overscanning and placement. In particular we noticed that three to four percent of the display was cut off at the edges. We also noticed that the screen seemed to be slightly shifted down and to the right. Unfortunatelly we were unable to get the TV to scan correctly using any of the options available, so you're just going to have to live with this. Luckily most 480p content is meant to be slightly overscanned so this isn't a huge issue.
720p (8.0)
With 720p content we saw none of the overscanning and alignment issues we saw with 480p content. We also found that resolution was very good, with no moire patterns causing blotches or discoloration. Legibility was also very good, once again only the smallest font sizes we tested showed any problems.
1080i (7.5)
Most broadcast HD content comes in 1080i format, so this is a particularly important test if you want to watch HD content from your cable or satellite provider. We found that the Vizio SV470XVT showed no overscanning while legibility and resolution were both good. Where we did detect a problem, however, was with moire patterns appearing in tightly packed patterns. The Vizio SV470XVT's showed a distinct greenish cast to most of our test patterns. We should also note that we noticed even more obvious blotches on the display when the Smooth Motion feature was turned on, we recommend turning this off in the settings.
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