Toshiba Regza 40XV645U LCD HDTV Review - Color Accuracy |
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Published on June 18, 2009 Comment on this |
Color Temperature (6.69) Like stars, which can range from blue hot to cool red, the light given off by your television can also have a color cast depending upon it's temperature. When we calibrated our HDTVs we try and set the color temperature as close to 6500 Kelvin as possible. Ideally this color temperature should not vary as the television ranges across the greyscal from deep greys to bright whites, which is what we look at in this test. Below you can see a graph of the Toshiba Regza 40XV645U's performance in this test.
You can see that the 40XV645U had some problems with the color temperature at the darker end, with a bluish cast appearing, which is a problem and results in the Toshiba Regza 40XV645U's less than impressive score in this test.
RGB Curves (5.82) All of the colors your HDTV produces are achieved by mixing different amounts of red, green and blue. As a result the performance of those three colors is very important in determining how well the Toshiba Regza 40XV645U produces colors. Below you can see a graph of the 40XV645U's red, green and blue color curves graphed against intensity.
You can see that the Toshiba Regza 40XV645U had some problems with color reproduction here. In particular the curves show some significant jagged and bumpy spots, most obvious in the blue but also present in red and green. This means that at points the 40XV645U will make innacurate adjustments in color. We also see that the HDTV makes very little differentiation in red and green at the lower end of the intensity scale. This can cause loss of detail in dark areas. At the same time we see that the blue curve never drops to zero, which probably explains some of the problems we saw with color temperature above. The overall result is simply a poor performance all around.
Color Gamut (5.20) All televisions must comform to a standard for how they reproduce colors, known as ITU Rec.709. This defines the color gamut for the television, which is the set of coordinates for all colors the HDTV can produce. The purpose is to ensure that the color the content producer wants you to see is actually the color that you see on your television. In this test we looked at how well the Toshiba Regza 40XV645U matched this standard. Below you can see a chart comparing the 40XV645U against Rec.709.
You can see that there are some significant problems, specifically in the blues and greens. What this means is that you won't see colors in those areas in exactly the way you are supposed to. To be fair to the Toshiba Regza 40XV645U very few HDTVs do a good job in this test, but the 40XV645U's performance is still at the lower end of a lackluster range. For those who are geeky enough to be interested you can see the exact color coordinates measured in the table below.
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• Variable color temperature
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