VIZIO VF550XVT

Color Temperature (9.82)
Just like stars, which give off white light in a variety of colors ranging from cool red to super-hot blue, televisions also have a temperature for the white light that they give off. In our calibration process we set the television to have a color temperature of 6500 Kelvin. A good television will keep this color temperature constant across the greyscale from the deepest greys all the way up to the brightest white. In this test we look at whether that is indeed the case with the Vizio VF550XVT.

Above you see a graph which plots the color temperature of the VF550XVT against the greyscale. Right in the center you see 6500 Kelvin, with the VF550XVT's performance graphed around it. You can see that there isn't a lot of variation away from the center, even once you get to darker greys, where we expect to see the greatest variation, the Vizio VF550XVT's performance in this test is very good compared to many other televisions.

The reason that we aren't concerned about the small amount of variation that we do see is because the human eye isn't super sensitive to variation in color temperature. Above you can see the same date form the first chart plotted slightly different. Each dot on the chart represents one of our readings. You can see that most of the data points lie right in the center of the chart, where we want them. More importantly they lie within the red circle. This circle represents the area within which variation in color temperature is not discernible to the human eye. You can see clearly here that the vast majority of the Vizio VF550XVT's data points lie within that circle. In fact the VF550XVT's performance is amongst the best we've ever seen from a television in this test.

RGB Curve (7.86)
All colors produced by an HDTV are created using combinations of three different colors: red, green and blue. In this test we look at the accuracy of those colors, which is obviously very important. Below you can see each of these colors graphed in intensity. What we're looking for here is a smooth, slightly concave curve that moves up steadily all the way to the end.

You can see that for the most part the Vizio VF550XVT's curves look good. There is a very slight slackening off at the top of the red curve and a more pronounced plateau at the top of the blue curve, but this is very minor. Unfortunately the Vizio VF550XVT did lose some points here due to a processing issue that we noticed.

This occurs when there are alternating black and white lines on the display. In many instances we noticed a very strong and noticeable greenish tinge when this occurs. Although this won't cause problems all the time, it will be very noticeable in some scenes, enough that we chose to deduct half a point from the VF550XVT's score in this section. If the Vizio VF550XVT hadn't shown this problem it would have put up a score well above average, as it is color performance is still above average, but only slightly.

Color Gamut (5.05)
All televisions are designed to produce colors in the same color gamut according to an international standard known as ITU Recommendation .709. This is done so that when a television receives a signal to produce a certain color it actually produces the color that the creator of the content expects. In this test we look at how closely the Vizio VF550XVT's color gamut matches this standard. Below you see the results of our test graphed.

What the graph above tells us is that the Vizio VF550XVT's color gamut (represented by a solid line) does not match up exactly with Recommendation .709 (represented by a dashed line). In particular you can see that there's some significant error in the blue and greens. What this means in practice is that these colors will be 'off' compared to what the creator of the content actually wanted to show you. Many televisions have problems producing color gamut correctly, and we've seen worse performance than this before. That said the VF550XVT's performance in this test is below average.

	u' (rec.709 / tested)	v' (Rec.709 / tested)	Error
Red	0.4507 / 0.4485	0.5229 / 0.522	0.002376973
Green	0.125 / 0.1181	0.5625 / 0.5631	0.006926038
Blue	0.1754 / 0.1657	0.1579 / 0.1662	0.012766362
D65	0.1978 / 0.1929	0.4683 / 0.4804	0.013054501

For those who like the raw numbers, the chart above gives you the exact color coordinates and error of our measurements.