VIZIO VL420M

Black Level (5.28)

We measured the darkest black that the VL420M could produce at 0.35 cd/m2. This is on the high side, and shows that some of the light from the back light is making its way through the LCD panel. Although LCD screens typically don't produce great black levels, many other displays manage better black levels than this, which leads to a more dramatic picture.

Black Level
Compare the Vizio VL420M to other HDTVs
Panasonic TC-P42S1 42'	Samsung LN40B610 40'	Sony KDL-40W5100 40'

Peak Brightness (8.38)

At the other end of the scale, we measured the brightest white that this display could produce at 305.16 cd/m2. This is a decent score, but it is darker than many other LCDs; both the Samsung LN40B610 and the Sony KDL-40W5100 had peak brightness measurements higher than 400 cd/m2.

Peak Brightness

Contrast (5.77)

The ratio between the brightest white and the darkest black is called the contrast ratio, and indicates the range of brightness that the display cam manage. We measured the contrast ratio of the VL420M at 847:1. This is on the low side of the ranges that we typically see, and means that the images on the screen will lack impact.

Contrast

Our contrast ratio measurements differ from the ones quoted by the manufacturers because they typically measure the black level with the backlight turned down and the peak brightness with it turned up, which produces a much wider ratio. But this doesn't refect the real performance you will see from a display, while our measurements do.

Tunnel Contrast (9.92)

Blacks and whites don't exist on the screen on their own. Instead, you see them side by side, so we measure how well the blacks hold up as they are surrounded by more and more white. On some displays, the blacks become brighter when there is more white on the screen, so that's what we test for. We didn't see a problem on the VL420M, though; the blacks remained constant across most of our test, with only a very slight increase in the black level when the screen was 95% white.

Tunnel Contrast

White Falloff (9.88)

The other thing that we test here is how constant the whites are as there is more and more white on the screen. On some displays (particularly plasmas), the brightness falls off as there is more and more white on the screen, but this wasn't a problem on the VL420M; the whites had no significant change when we went from just 5% white right up to a completely white screen.

White Falloff

Uniformity (7.0)

We found that the screen of the VL420M had decent uniformity, but there were a few issues. On black screens,  the edges of the screen were a little brighter than the corners, while on white screens the corners were a little paler than the center. However, these issues were fairly minor, and the changes in brightness were subtle and gradual; there were none of the sudden shifts that can be a real problem in everyday viewing.

Greyscale Gamma (7.86)

The greyscale gamma of a display is a measure of how quickly it goes from black to white. If the gamma is too high, the image will come out as being too grey. If it is too low, you won't see the subtle dark details. We measured the gamma of this display at 2.56, which is a little high: we look for an ideal gamma of between 2.2 and 2.3. But that's not high enough to be a serious issue.

Greyscale Gamma

Resolution Scaling (6.81)

The VL420M is a full 1080p display, but it doesn't always have the luxury of being able to work with this highest of all HD resolution signals. Instead, it often has to display a lower resolution signal, which is why we test it with a number of different signals to see how well it can upscale them to fit onto the screen.

480p (7.68)
480p signals (such as those produced by standard definition DVD players with HDMI outputs) were overscanned by about 3%, which is normal, and we saw no major problems with the upscaling that the display did.

720p (5.5)
720p signals did not look as good, though; we saw some problems with lines becoming rather jagged and complex patterns looked smudged and inaccurate. There was no overscan in the Full aspect ratio mode, which the display chose by default.

1080i (7.5)
Interlaced signals in the 1080i format outputted by most cable and satellite devices generally looked good, although there was some slight smudging caused by the interlacing. Again, there was no overscan.

Other Models in the VL Series
This is a review of the Vizio VL420M. The other sizes of HDTVs in this series should be similar in terms of performance and usability. For details about any differences, click on the image to jump to the Series Comparison page.
VL260M 26'	VL320M 32'	VL370M 37'	VL470M 47'