Vizio SV471XVT HDTV Review - Blacks & Whites

Blacks & Whites Summary
• The SV471XVT had bright, clear whites • The black level was rather high, leading to muddy blacks • Tested using DisplayMate software
	Tour & Design	Page 3 of 18	Color Accuracy

Black Level (4.94)

Our first test looks at the black level, examining how dark the deepest blacks that the display can show are. We found that the SV471XVT had a slightly disappointing black level of 0.41 cd/m2, which is significantly higher than many other HDTVs. In particular, the Samsung LN46A750 had a much deeper black of 0.15 cd/m2, and the Sony KDL-46Z5100 was even lower at 0.08 cd/m2. What this means in practice is that blacks on the screen of the SV471XVT will look slightly muddy, which might affect the dramatic look of some movies.

Black Level

The black level is unchanged from the SV470XVT (the similar model from the previous year).

Peak Brightness (9.81)

The SV471XVT had no problems producing a bright screen, though; we measured the brightest white of this display at a tear-inducing 460.42 cd/m2, which is extremely bright and is the highest that we've seen from any display that we have tested. What this means is that you would have no problems watching this screen in the daytime; it is bright enough to be visible in most conditions, with the possible exception of the midday sun in the desert. This is also significantly brighter than the SV470XVT, so Vizio have obviously done some work behind the scenes to increase the brightness of the CCFL backlights that produce the light of this display.

Peak Brightness

Contrast (6.21)

The ratio between the black level and the peak brightness is the contrast ratio, which represents the range of bright to dark that the display can manage. The Vizio SV471XVT managed a contrast ratio of 1122:1, which is respectable, but not outstanding. This is due to the rather high black level, and this means that the contrast ratio is significantly less than other displays that have deeper blacks, such as the Samsung  (with a ratio of 2842:1) and the Sony (4240:1).

Contrast

Vizio claims a contrast ratio of 50,000:1when using their DCR (Dynamic Contrast Ratio) feature, where the backlight is turned down the the screen is mostly dark, reducing the black level. However, we found that this only happened when there was a very small amount of white on screen (such as when there is a single credit on screen), so it won't make any difference in normal use. As with all HDTVs, the manufacturer's specs on things like contrast ratios have to be taken with a very large pinch of salt, as they don't reflect the real experience of what you will get. Our tests do, which is why we find significantly different results from the manufacturer's claims.

Tunnel Contrast (9.46)

Blacks and whites don't appear on the screen, so in this test we look at how well the blacks hold up as they are surrounded by different amounts of white. On some displays, the blacks become brighter as more white is on screen because some light bounces around within the screen, but this didn't seem to be a big problem with the SV417XVT; as the graph below shows, the blacks remained pretty constant as they were surrounded by more and more white. This is not unusual; very few modern HDTVs have a serious problem here.

Tunnel Contrast

White Falloff (9.98)

The flip side of this is how bright the whites remain as there is more and more white on screen: on some displays (particularly Plasma displays) the brightness of the whites falls off as the amount of white on screen increases. But again, the SV471XVT did not have a big problem here; the white level remained constant from just a small patch of white up to the entire screen being white. Again, we dont' typically see many problems here on most displays.

White Falloff

Uniformity (8.0)

If you are watching a scene of polar bear cubs frolicking in the snow, you want the snow to look the same across the screen. That doesn't happen on all displays; some have areas of the screen where the whites are paler, because of an uneven backlight or other problems. The SV471XVT had a slight issue here: in a clean white screen, we saw that the corners of the screen were significantly dimmer than the center, and that there were some slight patches of paler white at the left and right edges of the screen. With a black screen, the situation was reversed; the edges of the screen were slightly brighter. There were, however, no problems with blotches or patches of light or dark in the center of the screen, and the corner light/dark effect was a gradual fade; there were no sudden jumps from light to dark. This means that you are unlikely to notice the effect when watching a film.

Greyscale Gamma (7.57)

The greyscale gamma of a HDTV is how quickly the display goes from black to white. If it goes too quickly, images display will look too bright and washed out. If it goes too slowly, the images will look too dark. The about right spot is between 2.1 and 2.2, but the SV471XVT is a little on the high side at 2.6.

Greyscale Gamma

Resolution Scaling (7.38)

The SV471XVT is a 1080p screen, but it won't always get to work with this top of the line HD signal. Instead, it has to display images at lower resolutions, such as the 1080i signal that most cable and set-top boxes deliver. So, we test how well the display can deal with scaling these images to fit its 1920 by 1080 resolution screen.

480p (7.15)
480p signals come from standard definition video sources with digital outputs, such as a standard definition DVD player with a HDMI input. We found that these signals generally looked good on the this display; the text was sharp and there were only minor issues with the upscaling of the image causing . 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, and that it wasn't even: more was cut off at the bottom and right side than at the top and left. This isn't unusual with a 480p signal, but the only way to avoid the overscanning is to use the Normal mode, which sets the screen to a 4:3 aspect ratio, like a standard definition display. It is worth remembering that most 480p content is meant to be slightly overscanned so this isn't a big problem, though.

720p (8.0)
With 720p content we saw none of the overscanning and alignment issues we saw with 480p content; the display switched to a full screen mode that had no overscan. If you want overscan, ou can add it by switching to the Zoom 1 (for about 3%) or Zoom 2 (for about 14%) modes. 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  HD content comes in 1080i format: it is used by over the air DTV stations, and most satellite and cable systems. We found that the Vizio SV471XVT did a good job of dealing with these signals; text and complex patterns looked good, and there was no overscan. We did see some small issues, though; a complex moire pattern of alternating black and white dots on our screen had a slight greenish cast caused by the display trying to smooth out the image, which would show in video as a possible slight fringing effect on sharp edges.

Compare the Vizio SV471XVT to other HDTVs
Samsung LN46A750 46 inches	Sony KDL-46Z5100 46 inches	Vizio SV470XVT 47 inches