Sony Bravia KDL-46W4100

Color Temperature (9.38)
A good HDTV should be able to pick a white, and stick with it. Unfortunately, many don't; what starts out as white gets a color cast when the intensity of the white falls, turning whites slightly bluish or yellowish as they get darker. That's what we test here; we set the color temperature of the display as close to 6500k as we can at peak intensity, then measure the color temperature and color values for screens of different intensity levels. The results are on the graph below; the middle of the graph is the color temperature at the highest intensity, and the line shows how it varies going from the brightest white (on the left) to nearly black (on the right).

The 46W4100 did a very good job here; the color temperature of the whites remained pretty much constant across the range, only veering slightly at the bottom end of the scale, where it took a slight turn to the warmer side of things. But this was a pretty minor issue. Another way to look at this test is to look at the real color information, and this is a more accurate way to look at it. On the graph below, the brightest white color value is at the center of the graph, and the test results are the points. The red circle is the minimum amount of color change that most people can see; if a point falls inside this circle, you aren't likely to be able to spot the difference. As you can see, most of the points fall in or on the circle, meaning that the differences aren't really noticeable. Only a few points fall outside the circle underlining that the 46W4100 had good performance in this test; the whites start out and remain white.

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

Setting	Color Temperature
Cool	11897
Neutral (default)	9729
Warm 1	8345
Warm 2	6650

We used the Warm 2 mode for our tests, as it came closest to the 6500k color temperature that we use for testing.

RGB Curve (8.27)
Like all HDTVs, the 46W4100 makes colors by mixing the three primary colors; yellows are made by turning on the red and green elements of the screen, and white by turning on all three. For accurate colors, it is important that all three colors respond in the same way, evenly going from dim to bright. That's what we test here; our sophisticated testing system allows us to analyze the response of each of the primary colors. The results are plotted on the graphs below.

The 46W4100 had the kind of curves that downhill skiers dream of; smooth slopes without any big jumps or hidden crevices. And this works well for viewers as well; the smooth curves mean that subtle changes in colors will be accurately represented. And this came across when looking at test images such as photos; subtle color details like clothing and blue skies looked great, with all of the fine color details being accurately represented. The only issue we saw was a very slight amount of clipping on the red, where the color peaks too soon. But this is a very minor issue and shouldn't affect image quality much.

Color Gamut (5.32)
There are well-defined limits to what colors a HDTV signal should contain; a group of imaging eggheads set them in a standard called ITU-R Rec.709. So, we test how well the colors that HDTVs can manage match up with this; the results are below. On this graph, the limits in the standard are the dotted line, and the limits of the colors that the 46W4100 could display are shown by the solid line.

The Sony Bravia 46W4100 had a few issues here; although the red corner of the gamut is very close to the ideal, both the green and blue are a bit off, meaning that blues and greens could be slightly inaccurate. These inaccuracies are a problem; color gamut errors shift the colors into areas that the director of the movie or show didn't intend, and greens and blues will look slightly greener and bluer than they should. For fans of the technical side of things, we list the measured color values of all of the primaries and the D65 value below, as well as the error (the difference between the ideal and the measured).

	u' (rec.709 / tested)	v' (Rec.709 / tested)	Error
Red	0.4507 / 0.449	0.5229 / 0.5241	0.002
Green	0.125 / 0.1163	0.5625 / 0.5621	0.008
Blue	0.1754 / 0.1778	0.1579 / 0.1423	0.015
D65	0.1.978 / 0.1947	0.4683 / 0.0.4698	0.015