VIZIO VL420M

Color Temperature (6.72)

The color of the white on  a display is measured in something called the color temperature. As part of our calibration procedure, we set the color temperature of the brightest white to as close to 6500k as possible, but it is also important that a display has consistent color temperature with greys. In some displays, we see a distinct shift here, which gives some shades of grey a significant color cast. The VL420M has a bit of an issue here: as we got closer to black, we saw a distinct shift in the color of the greys towards the blue.

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

RGB Curves (7.27)

Like all HDTVs, the VL420M produces the colors you see on screen by mixing the primary colors of red, green and blue. So, it is important that a display be able to accurately reproduce subtle changes in these colors, which is what we test here. We feed the HDTV a signal that contains gradually increasing intensities of red, green and blue from 0 (minimum) to 255 (maximum) and measure the luminance of the colors on the screen. We then plot this onto the graph below. The ideal here would be a perfectly smooth curve, but no display manages this; because of the way they process signals, the curve has bumps and jumps.

RGB Curves

There were two main issues with the curves for the VL420M; the curves themselves are a little bumpier than we like to see, and there is some peaking. This is where the curve tops out; although the signal is getting brighter, the screen has already produced its maximum luminance. This can mean that some subtle details in bright colors get lost, such as the folds in a bright red uniform, or the veins on a bright green leaf. However, the peaking is not particualrly bad (especially with our calibrated settings, where we adjusted the RGB controls to compensate), so you are not likely to see much of an issue in everyday use.

We also create the strips below that show this curve on a gradient from the brightest color to black. The top strip is an ideal version; if you see significant banding on this, the device you are reading this review on may have a poor response curve or other issue.

Red Response Comparisons
Ideal Response
Vizio VL420M
Panasonic TC-P42S1
Samsung LN40B610
Sony KDL-40W5100

Green Response Comparisons
Ideal Response
Vizio VL420M
Panasonic TC-P42S1
Samsung LN40B610
Sony KDL-40W5100

Blue Response Comparisons
Ideal Response
Vizio VL420M
Panasonic TC-P42S1
Samsung LN40B610
Sony KDL-40W5100

Color Gamut (4.95)

The range of colors that a display can reproduce (the color gamut) should ideally be the same as the range of colors that a HDTV signal should contain. This is defined in an international standard called rec.709, so we measure the color gamut of the display against this. For the VL420M, we saw a few issues here, such as a slight error on the green and the more significant error on the white point.

Color Gamut

For those who like to know the precise details of our test results, the color co-ordiantes of the rec.709 standard and our test results are below.

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'