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We were happy with the brigthest white on the Panasonic TC-37LZ85 and we also liked how well both blacks and whites held up. What wasn't impressive was the poor black level and erratic gamma curve.
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Black Level (5.04) 
How deep a televisions blacks are displayed is an important consideration, you don't want what us is supposed to be black on the screen to look washed out or grey. We measured the deepest black on the Panasonic TC-37LZ85 using our calibrated settings at 0.39 candelas per meter squared (cd/m2). This is rather mediocre performance, even for an LCD television, whose blacks tend to not be as deep as plasma televisions. We've seen significantly deeper blacks from other LCD HDTVs like the Samsung LN32A450 (0.14 cd/m2) and the JVC LT-32P679 (0.12 cd/m2), amongst others. We would have much preferred to see some deeper blacks on the Panasonic TC-37LZ85.
Peak Brightness (9.26)
In this test we look at the brightest white on the Panasonic TC-37LZ85 using our calibrated settings. We measured this peak brightness at 393.78 cd/m2. This is a very good score, in fact it's amongst the best we've seen from any HDTV, only the Sharp Aquos LC-46D64U has put up a similar peak brightness while the Samsung LN46A750 is the only HDTV we've seen that beats it handily. Users should be very happy with the Panasonic TC-37LZ85's peak brightness.
Contrast (6.04)
Contrast is the ratio between the brightest white and darkest black. If you want to do a little bit of math you can figure this out on your own with our previous two scores. If you don't feel like pulling out a calculator we'll just tell you that the Panasonic TC-37LZ85's contrast ratio was 1:1010. This is an unimpressive contrast ratio, but not the worst we've ever seen either. For example both the Vizio VO47L and the JVC Procision LT-47X899 performed significantly worse. Most HDTVs do better, however. In the case of the Panasonic TC-37LZ85 the big stumbling block for the contrast ratio is obviously the poor black level.
Tunnel Contrast (9.27)
We're not only interested in how dark the Panasonic TC-37LZ85 gets, but also want to know how well the deepest blacks hold up when paired with bright whites. That is what we look at in this test as we measure the black level while steadily increasing the amount of white on the screen. Below you can see a graph of what happens to the black level as we do this.
You can see from the relatively flat line that the Panasonic TC-37LZ85 does a solid job here. The change in black level is minimal, going from 0.39 to 0.47 as we add more and more white to the scene. What this means for viewers is that you're going to get stable blacks regardless of what other colors are in a scene. Now if only that black could have started a bit lower...
White Falloff (9.03)
This test is the opposite of the tunnel contrast test, here we look at how well the brightest white holds up as we increase the amount of black on the screen. Below is a graph of white falloff for the Panasonic TC-37LZ85.
You can see that although there are a couple of bumps in the graph there are no major shifts that would indicate serious variation. In fact the peak brightness varied by less than 1% between the 100% white screen and the 5% white screen, indicating that the peak brightness holds up very well.
Uniformity (6.0)
Here we look at how uniformly the display is able to reproduce blacks and whites. With the Panasonic TC-37LZ85 we noticed some significant problems, particularly with blacks. An all white screen showed some common issues such as a bit of dimming at the corners and edges, things we see on many HDTVs. When looking at a black screen on the Panasonic TC-37LZ85, however, we saw significant blotches in the middle of the display and much more leakage than we would have liked, especially along the bottom edge.
Greyscale Gamma (5.14)
Update: We have rescaled our scoring for this section. The original score was 0.0.
In this test we look at how smoothly the Panasonic TC-37LZ85 makes adjustments from white to black, known as the gamma curve. Below you can see the Panasonic TC-37LZ85's curve displayed.
This curve is relatively smooth, but it hides some problems. The human eye doesn't actually pick up gradual changes, instead it picks up exponential changes in gamma, which we graph in the curve below.
Here you can see that the Panasonic TC-37LZ85 had some significant problems, especially as it made transitions across darker greys. These problems were serious enough that the Panasonic TC-37LZ85 failed our test, receiving a score of zero. It should be noted, however, that the major problems are concentrated amongst variation in the darker greys and most of the transitions the HDTV makes are much smoother.
Resolution Scaling (7.83)
Video content comes in a dizzying array of resolutions. The Panasonic TC-37LZ85 is a 1080p television, which means it natively displays content at that resolution. It will have to deal with other resolutions, however, and that is what we look at below.
480p (7.75)
480p content is what you get from traditional standard definition television broadcasts and DVDs. The Panasonic TC-37LZ85 did a decent job with 480p content, however we did note that it had problems with overscanning. What this means is that you will lose as much as 5% of the content both vertically and horiztonally on the display.
720p (7.75)
At this level we are starting to get into the base of what is known as HD content. 720p is used for a lot of online HD video and many over the air sports broadcasts are also in this format. We saw solid performance with legibility and resolution with this format, but once again we noted that overscanning is a problem with up to 5% of the display being cut off vertically and horizontally.
1080i (8.0)
The difference between 1080i and 1080p is in how the signal is displayed on the HDTV. With a 1080i signal you alternate between two signals of 540 lines each, the first signal gives you the odd lines and the second the even. 1080p signals give you all 1080 lines at once. Because less information is transmitted at one time with 1080i it is often the signal used by broadcast HD. Thankfully the Panasonic TC-37LZ85 did a very good job with 1080i signals, it avoided many of the pitfalls we've seen on other HDTVs with 1080i, including a shutter effect in high contrast areas. We were very happy with the Panasonic TC-37LZ85's handling of 1080i content.
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