VIZIO VO47L

Color Temperature (9.64)
Your washing machine might make your whites whiter than white, but your television should not; you want a TV that keeps your whites the same, however bright they are. So, we test the color temperature performance of displays such as the VO47L by looking at how similar the whites it displays are at differing intensities. To do this, we calibrate the TV to produce a white at as close to 6500k as possible at the maximum intensity of white, then gradually reduce the intensity of the white and see how much the color temperature varies. The graph below represents the results of this test; a perfect display would have a completely flat curve here, indicating that the color temperature did not change as the intensity of the white decreased.

As you can see from this, the VO47L did a very decent job; the variations of the color temperature as the intensity of the white decreases are very small. In fact, the differences are so small that they aren't perceptible. Another way to look at this is to look at the color values of the white instead of the color temperature; if the color of the white changes significantly, you'll see a color cast. The graph below shows this; the center of the graph is the color of the white at maximum intensity, and our measurements of the white as the intensity decreases are shown on the black line. The red line indicates the smallest color difference that the human eye can perceive. On this chart, a perfect TV would have all of the measurements in the center.

The VO47L did well here again; most of the measured points (the dots) are within the red line, and the ones that are outside of it are only just outside. This means that there are some color shifts in the whites, but only minor ones that should not be visible to most people.

We also test the color temperature of the various color temperature modes that the display offers; the results are below.

Setting	Color Temperature
Cool	8582
Normal (default)	5596
Warm	5014

Because none of the built-in settings were close to our ideal target of 6500k, we used a custom color temperature setting that got us significantly closer.

RGB Curve (7.59)
Televisions make the colors that you see on the screen by mixing the three primary colors: red, green and blue. So, it is important for the performance of a HDTV that the response of each of these colors is smooth and accurate; any issues with one of the primary colors  would lead to every color that was made using that primary coming out wrong. So, that's why we look at the response curve of each of the primary colors individually by measuring a number of test screens. The results from these tests are shown below.

As you can see from this, the graphs are all fairly smooth, although the red and blue are a little bumpy. This bumpiness translates into some minor issues, such as some slight evidence of banding on subtle color changes like blue skies and clothing. The blue also tops out a little soon, meaning that the blue elements of the screen reach their peak intensity before the signal does; they just have no more to give. This is a minor issue, though; we would not expect this to present a problem in daily viewing. Overall, the Vizio VO47LF had decent, but unspectacular performance on the RGB curves.

Color Gamut (6.0)
There are limits to most things in life, including color. For a HDTV, the limits to follow are defined by a group of international experts in a standard called Rec.709. This contains the limits of the colors that a HDTV signal should contain, and thus represent what colors a TV should show. So we test this and see how close every TV we look at gets to these limits. The results for the Vizio VO47LF are below; the solid line is the limits for the Vizio, while the dotted line is the limits set in the standard.

Again, the VO47LF did reasonably well here; it didn't hit the limits right on, but it did get pretty close; the main errors are in the green and blue, both of which are slightly off.  For all of you imaging geeks out there, the chromaticity coordinates for our tests are in the chart below, as well as the error (the difference between the ideal and the measured).

	X (rec.709 / tested)	Y (Rec.709 / tested)	Error
Red	0.4507 / 0.452	0.5229 / 0.5234	0.0013
Green	0.125 / 0.1195	0.5625 / 0.5639	0.0056
Blue	0.1754 / 0.1702	0.1579 / 0.1565	0.0053
D65	0.1.978 / 0.2049	0.4683 / 0.4766	0.0109