Sharp Aquos LC-40E67UN LCD HDTV Review - Color Accuracy |
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Published on August 18, 2009 Comment on this |
Color Temperature (9.22) In this test, we look at how consistent the whites are: as they go from the brightest white to gray, are there any shifts in the color of the white that could lead to colored greys? We didn't see any serious issues here with the LC-40E67EU; the whites remained mostly constant, with only a slight error at the lower end of the intensity range. As part of our calibration process, we set the color temperature of the brightest whites to as close to 6500k as possible: we found on this display that the closest we could get was the warm color temperature mode, which we measured at about 6100 degrees kelvin.
RGB Curves (8.8) All HDTVs create the colors you see on screen by mixing the primary colors of red, green and blue. So, it is important that a display is able to represent the subtle changes in these colors that images contain to produce accurate colors. We found a few minor issues here, but overall the LC-40E67EU did pretty well. The RGB curves were mostly smooth, although there were some bumps in the RGB curves that could translate into problems reproducing subtle color changes. We test this by outputting a signal containing all of the different color intensities from 0 to 255 (the complete range that a HD signal can contain) and measuring the intensity of the color on the screen. We then plot this to produce the color response curve.
On a perfect display, this curve would be completely smooth, meaning that every slight change in the signal was reproduced. In practice, we find that most displays have slightly bumpy response curves, but the LC-40E67EU is no bumpier than most that we see; there are some bumps and jumps in the response curves, but these are small and didn't translate into problems in real world use, as our test photos that include subtle color changes mostly looked fine, with no problems in reproducing the fine details of things such as sunsets, flowers, etc. Another way to look at these results is to create a gradient that shows the response curve in action.
Color Gamut (5.29) The total range of colors that a display can reproduce is called the color gamut. What thsi gamut should be is defined in an international standard called Rec.709, so we test how close a HDTV gets to these limits. The answer for the 40E67EU is not that close; we found that while the blue was almost spot on, both the red and green corners of the gamut had errors. On the green corner, the colors are too intense, while on the red corner they are a little too pale. These errors are not likely to be particularly visible unless you are looking at this HDTV next to one with a more accurate color gamut, but they are definitely there.
For those who are fans of chromaticity coordinates, both the Rec.709 and our measurements are shown below.
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• Consistent whites
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