Samsung LN40B650

Black Level (8.77)

We measured the Samsung LN40B650's black level at 0.07 candelas per meter squared (cd/m2). This is an excellent black level, especially for an LCD HDTV, which tend to have more trouble producing deep blacks than Plasma televisions. You can see in our comparison chart below that the LN40B650 actually produced deeper blacks than Samsung's plasma model the PN50A760. It obviously produced much better black levels than the other two LCD models in our comparisons.

Deep blacks are important as it allows an HDTV to produce much more contrast between dark and bright areas of the display.

Peak Brightness (9.01

)

The Samsung LN40B650's peak brightness was measured at 365.79 cd/m2. This is the brightest white that we could produce on the HDTV using our calibrated settings. This is an excellent peak brightness, amongst the best we've seen from an HDTV. Below you can see that the Samsung LN40B650 outpaces all of our comparison televisions. In particular note that the peak brightness of the LCD LN40B650 is more than twice that of the plasma Samsung PN50A760. This highlights one of the problems of plasma televisions, that they are not capable of producing as bright an image as their LCD counterparts.

Contrast (9.26)

The Samsung LN40B650's contrast ratio of 5226:1 is simply the best we've ever measured to date. This excellent contrast ratio is due to the very deep blacks and very bright whites that the LN40B650 is capable of producing. Below you can see that the Samsung LN40B650 far outpaces our comparison HDTVs in this area.

Contrast is very important because the human eye is very sensitive to contrast. The more contrast an HDTV is capable of producing the better it's going to look to you.

Tunnel Contrast (9.85)

In this test we look at what happens to the black level of the HDTV as we put less and less black on the screen. You can see from our chart below that the Samsung LN40B650 does a very good job in this area, with black level staying very low even when 95% of the display is white and only 5% is black. This is important because in real life you don't view a 100% black screen, rather dark regions are going to be mixed together with bright regions. This tells us that the Samsung LN40B650 will be able to continue producing very good blacks even in mixed content.

White Falloff (9.96)

In this test we look at how well the peak brightness holds up as a progressively smaller percentage of the screen is white. The Samsung LN40B650 did very well in this test, with the peak brightness holding up even when the screen was 5% white and 95% black. White falloff usually isn't a problem with LCD HDTVs, so we're not surprised to see the LN40B650 do well here.

Uniformity (7.5)

We looked at how uniform the Samsung LN40B650's display was with both an all black screen and an all white screen. The white screen looked excellent, with very little dimming at the corners and edges and no problems with blotches or lack of uniformity across the center of the display. The all black screen had a bit more trouble. We noticed some very noticeable brightening at the corners and at a spot right near the bottom center. Almost all LCD HDTVs display some brightening at the corners and the LN40B650's brightening didn't take up as much of the display as we've seen on other televisions, but it was very noticeable with the dark screen.

Greyscale Gamma (8.79)

Note: we made an error in calibration that we have corrected since publication, as such the score in this section has changed. The original score was 5.56.

We measured the Samsung LN40B650's gamma at 2.4. This is slightly higher than the 2.1 to 2.2 gamma that we look for on HDTVs. The steeper gamma curve means that the LN40B650 makes adjustments along the greyscale a bit more aggressively than we would like, but this shouldn't be a serious issue. We should note that when we first tested the LN40B650 we measured its gamma at 2.94. Adjusting the gamma option up to +3, however, produced a significantly better result.

Resolution Scaling (8.4)

The Samsung LN40B650 supports the highest quality of HD content, known as 1080p. This means that the content has 1080 lines from top to bottom and displays all of the lines progressively, rather than interlacing them. Unfortunately the only place you can get 1080p content for your HDTV is from a Blu-ray disc. Most of the content you'll watch comes in different formats, and here we look at how well the LN40B650 handles those formats.

480p/i (9.2)
480p content is what you get from DVDs, while 408i is what you get from standard definition television. In both cases there are 480 lines of content from top to bottom, so a 1080p television like the Samsung LN40B650 needs to upscale this content to fit on the larger number of pixels. The LN40B650 did a good job with this process as we noticed no problems with legibility, resolution or moire patterns, which sometimes appear in complex patterns when upscaling is not done correctly. We did notice a mild overscane of 3% on all sides, which means that 3% of the picture is cut off.

720p (8.0)
720p is the lowest quality of high definition content, with 720 lines displayed progressively from top to bottom. This format is the standard for high definition content you get online and is sometimes used by HD broadcasts instead of 1080i because the progressive signal is better able to display fast motion than the interlaced signal of 1080i. The Samsung LN40B650 had obvious problem with 720p content, vertical banding appearing in complex patterns. There were no problems with legibility, resolution and interestingly there were no overscan issues. The vertical banding, however, could be very annoying if you happen to be viewing content with a pattern that the LN40B650 has trouble with.

1080i (8.0)
1080i has the same 1080 lines from top to bottom that 1080p content does, but instead of displaying all the lines at once 1080i interlaces two sets of 540 lines. This reduces the bandwidth necessary to transmit the signal and this is why 1080i is used as the standard for broadcast HD. Unfortunately the interlace process can also produce some negative effects if the processing is not done well. On the Samsung LN40B650 the only major problem we noticed was that the HDTV had trouble resolving very tightly packed patterns. We saw no problem with legibility and no moire patterns appeared.