Sony Bravia KDL-46W4100

Black Level (8.23)
The Bravia 46W4100 had impressively deep blacks; we measured the deepest black in normal use at 0.09 cd/m2 (candelas per meter squared), which is significantly darker than many other LCD HDTVs we've tested; the JVC LT-47X899 had much lighter blacks at 0.37 cd/m2. This impressively deep black means that the dark scenes of movies should look suitably dark and gloomy. However, Sony didn't seem happy with this; if the image on the screen is almost completely black (such as credits on a movie or a documentary about bats in coal mines), the display takes it a step further by turning down the backlight, which takes the black level further down to around 0.1 cd/m2. It does this after just a couple of seconds of dark video, so it could come as something of a surprise; other displays (such as the JVC LT-47X899) have similar features, but they only kick in after 15 to 20 seconds. Peak Brightness (8.10)
At the other end of the brightness spectrum, the 46W4100 had an equally impressive result; we measured the peak brightness at 282 cd/m2, which is pretty bright. It's not the brightest on the block (of the displays we've tested so far, that title belongs to the Samsung LN-46A750, which turned it up to 11 in brightness terms with a peak brightness of 426.3 cd/m2. But the 46W4100 had very strong brightness, which should be enough to keep the screen visible in all but direct sunlight. Contrast (8.11)
With the deep blacks and bright whites, it's no surprise that the contrast ratio of the 46W4100 was a very impressive 3133:1. That beats most of the other displays that we've looked at; only the Samsung LN-46A750 comes close at 2842:1. Tunnel Contrast (8.57)
Blacks and whites seldom exist alone in a video; they are usually on the screen together. And that's why we test tunnel contrast, which looks at how deep the blacks stay when there is white nearby. We do this by testing a number of screens with variable amounts of white, testing how deep the blacks remain. Again, the 46W4100 did well here; we found that the blacks did get a little lighter as they were surrounded by more and more white, but only by a small amount; when the screen was 95% white, the black level rose to 0.21 cd/m2. White Falloff (9.46)
Displaying a lot of white on the screen can take it out of a display; the more white, the paler some get because they need to try and control the heat that the display produces. This didn't seem to be a problem for the 46W4100; when we tested the white falloff, we found that the luminance of the white remained pretty much constant however much of it there was on the screen. Uniformity (7.04)
The 46W4100 had a few minor issues when it came to the uniformity of the screen; we saw some minor problems on both our black and white test screens. On the white screens, the right and left side of the display was not as bright as the center, and on the dark screens, there was a slight but noticeable series of patches of lightness that gave the screens a mottled, almost diseased look. However, both of these issues were minor; although they were visible on our test screens, they did not detract from the quality of our test video clips. Grayscale Gamma (7.72)
Update: We have rescaled our scoring for this section. The original score was 8.37.

The ideal gamma for a television is between 2.4 and 2.5, and we found that the 46W4100 fell just outside this range, with a gamma of 2.58. We determine the gamma by measuring a number of screens with different levels of intensity, ranging from nearly black up to the brightest white that the display can work with.

This graph is a little easier to understand if we plot it on a log-log axis. On this graph, the perfect display would have a flat curve.

The 46W4100 does a very decent job here; the line is smooth and almost flat and doesn't have much in the way of bumps or sudden jumps that might indicate a processing problem. Overall, it did a very decent job of going from black to white smoothly and cleanly.

Resolution Scaling (7.33)
The 46W4100 is a 1080p display with the full 1080p resolution, but it doesn't always get a 1080p signal to display; many devices produce lower resolution signals, and the display has to scale these to fit the screen. So, we test how good of a job the display does by feeding it a series of test screens in various high definition signal formats. Let's look at each of these in turn.

480p (7.30)
480p signals are produced by many standard definition devices that have digital outputs, such as DVD players or some standard definition cable boxes. We found that the 46W4100 did a very decent job of scaling this type of signal to fit the screen; the text in our test screens remained sharp and legible, and there was little evidence of moire patterns caused by the dithering that the display uses to scale the video up. The video was overscanned by about 4 per cent, which is pretty standard for this type of video.

720p (7.35)
720p high definition signals are often used by broadcasters when they are showing sports, as the progressive look (where each screen is transmitted in full, 29.97 times a second) provides smoother movement than 1080. That's important when you are showing a large number of burly men chasing a pigskin across the screen; smooth movement makes it easier to keep track of who has the ball. We found that the 46W4100 again did a decent job here; the images looked sharp and movement was smooth and easy to follow. Again, the image was overscanned (by about 3 per cent), and the setting to change this was rather buried in the menu; you have to go to the screen menu, then select display and choose the full pixel mode. We generally prefer for the default to be no overscan on 720p video; usually, there is no need for it, and it is a real pain if you are using the screen with a computer, as it cuts off the menus and buttons on the edge.

1080i (7.35)
1080i video is the most common form of high definition video; it's what most over the air high definition signals are sent in, and it's what most high definition cable boxes produce. The 46W4100 did a decent job here too; images were sharp and movement was smooth. However, this is the only HDTV we've seen that adds overscan to a 1080i signal by default; we saw about 3 per cent overscan. This can be removed, but it's a pain to do so (and the TV reverts to the default setting if it is unplugged), and we can see no good reason why it should default to this.