Sharp Aquos LC-46D64U

Black Level (6.61)
As a general rule, the deeper the black level of the TV, the better images will look. Deep, dark blacks make for more dramatic scenes and more realism. The Sharp was in the middle of the pack for black level, though; we measured it at 0.19 cd/m2 (candelas per meter squared, a standard measurement of luminance). That's pretty decent for an LCD HDTV; the JVC LT-47x899 hd much lighter blacks at 0.37 cd/m2, but the Sony Bravia 46w4100 was significantly better at 0.09 cd/m2. Peak Brightness (9.54)
The other side of the coin is peak brightness; the brightest white that the TV can manage. The Sharp had no shortage here; we measured it at an eye-watering 395.42 cd/m2. That's one of the brightest that we've seen; only the Samsung LN46A750 was brighter at 426.3 cd/m2. Of course, peak brightness is only part of the equation, but it is definitely nice to have the brightness there if it is needed for watching the TV in daylight. Contrast (7.91)
Contrast ratio is the balance between the light and the dark, and a TV with a good contrast ratio will look better overall. The Sharp LC46-D64U did well here; we measured the contrast ratio at 2842:1. Again, that's a strong score that is significantly higher than many other TVs; the Vizio VO47LF, for instance, managed just 713:1. Tunnel Contrast (9.19)
Whites and blacks seldom exist in isolation on the screen, which is why we test the tunnel contrast, where we look at how the blacks hold up when they are surrounded by white. We do this by measuring a small area of black in the middle of the screen and slowly increasing the amount of white around it. On some TVs the white bleeds into the black, but that didn't seem to be an issue on the LC-46D64U; we only saw a very slight increase in the black, even when the rest of the screen was white. White Falloff (9.42)
Some displays also have a problem with white; as the amount of white on the screen goes up, the display has to turn down the brightness to keep from overheating. This didn't seem to be an issue for the LC46-D64U; we did not see much variation in our tests with screens with different amounts of white. Uniformity (6.25)
Another important aspect of black and white performance is uniformity; an ideal screen wuld have exactly the same brightness all over the screen for both black and white screens. The LC-46D64U had a few problems here; we noticed that the corners on the white screen were less bright than the center of the screen, and that there were several vertical spots on the dark screen that were lighter as well. Grayscale Gamma (5.14)
Update: We have rescaled our scoring for this section. The original score was 1.0.

The LC46-D64U had some rather odd behavior here. When we plot our tests on how a display changes from from black to white as the intensity of the signal increases, we usually expect there to be a curve rather like a child's slide. Instead, the Sharp had a mostly flat curve, like a ski jump.

Another way to look at this is to plot the data onto a graph with logarithmic axis. On this graph, we would expect to see a nice straight line. Instead, we get an s-shaped curve (the blue line is the trend line we add). What this means in practice is that the grays on the screen are going to start out pale, then quickly get significantly darker, without that many shades of gray in between. This is borne out by our examination of a number of test screens; the mid tones of grey were more compressed than we like to see, with more subtle shades at either end of the range getting lost in the blacks and whites.

From this graph we can also extrapolate the gamma, which we would typically expect to see in the range of 2.4 to 2.5. For the Sharp, it is 3.01. This is a very odd result, and not in a good way.

Resolution Scaling (6.43)
The LC-46D64U is a 1080p screen, but it doesn't always get to display 1080p signals. It often has to work with lower resolution signals from devices such as cable boxes and DVD players, so we test how well it deals with taking these lower resolution signals and scaling them up to fit the 1080p screen.

480p (5.85)
480p signals are produced by many standard definition devices that have digital outputs, such as standard definition cable boxes, DVD players and some game consoled. The LC-46D64U didn't do a great job with these; we found that text looked a little soft, and that lined and edges were a little jaggier than some displays. The screens were overscanned by about 4 per cent; a fairly standard amount for this type of signal.

720p (6.85)
720p high definition signals (which are often used on sports broadcasts), as the progressive look (where each screen is transmitted in full, 29.97 times a second) looked a little better than their 480p cousins; the text in our test screens was sharper and edges were better defined. But the screens were overscanned again (by about 3 per cent), which is unnecessary with 720p and higher resolution signals. This is easy to deal with (press the view mode button on the remote and select the dot by dot mode), but it is annoying that the display defaults to an overscan mode.

1080i (7.35)
1080i video is the most common form of high definition video; it's what most over the air high definition TV signals are sent in, and it's what most high definition cable boxes output. The LC-46D64U did a decent job here; the images were sharp and we didn't see any major glitches from the deinterlacing that the display has to do to show the signal. But again, the image was overscanned by default for no good reason. And this is especially annoying as 1080i is a mode that's commonly used with a computer, but if the image is overscanned, you loose the menus on the edge of the screen. Again it's relatively easy to switch back to the dot by dot mode, but it is annoying that you have to do this.