Samsung LN40B650 LCD HDTV Review - Color Accuracy

Color Accuracy Summary
• Color temperature showed some yellow tinging in dark greys • RGB accuracy very good • Color gamut innacurate in the blues • Testing done with DisplayMate
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Color Temperature (8.11)

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 7.83.

Like any light emitting object the light given off by your HDTV has a certain temperature that can range from cool and yellow/red to hot and blue. We attempt to calibrate HDTVs to get as close to the industry standard color temperature of 6500 Kelvin (K) as possible. Ideally the color temperature will stay constant across the greyscale, so as the HDTV gives off any shade of grey from the darkest up to the brightest whites the color temperature will stay the same. In this test we look at how well the Samsung LN40B650 handled that. Below you see a graph of our measured color temperature for the LN40B650 across the greyscale.

You can see that the Samsung LN40B650 had some minor problem with colors getting warmer with darker greys. It is not uncommon to see HDTVs struggle a bit with color temperature at this extreme and the Samsung LN40B650's performance won't have too negative an impact on your viewing experience. You can see this more clearly in the chart below.

Here you see the same data from the curve above but this time graphed as points. The circle represents the range within the human eye can't detect changes in color temperature. You'll note that most points fall within that circle, which is exactly what we want to see. You may get a slightly yellow cast to very dark greys, but it likely won't be very noticeable.

RGB Curves (9.06)

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 9.05.

All the colors your HDTV produces are created by mixing different amounts of red, green and blue light. In this test we look at the accuracy of those three colors. Below you can see the curves for each of the three colors that we obtained from our testing of the Samsung LN40B650. The curves are concave and fairly smooth, which is exactly what we want to see. In addition there is no significant peaking, which we sometimes see in HDTVs and indicate an inability to differentiate between very bright shades of the color.

We also run through a variety of different test photos with HDTVs to try and detect artifacts, which are things that shouldn't be there but appear because of processing errors. Thankfully we detected no significant problems with the Samsung LN40B650. That combined with the smooth color curves and lack of peaking with intense colors produces an excellent color score for the Samsung LN40B650.

Color Gamut (5.36)

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 5.36.

In order to ensure that we get the colors we expect when watching content on our HDTVs all televisions must use an industry standard color gamut known as Rec.709. In this test we look at how well the Samsung LN40B650 matched this industry standard. Below you can see a graph of our results with the LN40B650's performance graphed against the standard.

You can see that the Samsung LN40B650 does a decent job of matching the color gamut in the red and green regions, but is significantly off in the blues. The end result is a score that's j average, frankly a lot of HDTVs struggle in this area, but the fact that almost all the error comes in a single color means that you can expect blues on the LN40B650 to be visibly off. That means that the blue the content creator wanted you to see is likelly not the blue you'll actually see on the LN40B650. For those who are geeky enough to care you can see the exact color coordinates and error that we saw on the Samsung LN40B650 in the table below.