Color Quality

Now let’s get to the meat of the display characteristics. As usual, we report two main quality metrics: color accuracy (Delta-E) and color gamut. Color gamut refers to the range of colors the display is able to represent with respect to some color space. In this case, our reference is the AdobeRGB 1998 color space, which is larger than the sRGB color space. So our percentages are reported with respect to this number, and larger is generally better.

Color accuracy (Delta E) refers to the display’s ability to display the correct color requested by the GPU and OS. The difference between the color represented by the display, and the color requested by the GPU is our Delta-E, and lower is better here. In practice, a Delta E under 1.0 is perfect - the chromatic sensitivity of the human eye is not great enough to distinguish a difference. Moving up, a Delta E of 2.0 or less is generally considered fit for use in a professional imaging environment - it isn’t perfect, but it’s hard to gauge the difference. Finally, Delta E of 4.0 and above is considered visible with the human eye. Of course, the big consideration here is frame of reference; unless you have another monitor or some print samples (color checker card) to compare your display with, you probably won’t notice. That is, until you print or view media on another monitor. Then the difference will no doubt be apparent.

As I mentioned in our earlier reviews, we’ve updated our display test bench. We’ve deprecated the Monaco Optix XR Pro colorimeter in favor of an Xrite i1D2 since there are no longer up-to-date drivers for modern platforms.

For these tests, we calibrate the display and try to obtain the best Delta-E we can get at both 200 nits of brightness for normal use, and 100 nits for print brightness. We target 6500K and a gamma of 2.2, but sometimes the best performance lies at native temperature and another gamma, so we try to find what the absolute best performance could be. We also take an uncalibrated measurement to show performance out of the box using either the manufacturer supplied color profile, or a generic one with no LUT data. For all of these, dynamic contrast is disabled.

Performance uncalibrated, entirely out of the box is actually very good, at a respectable 3.64. When I first started working on the VG236H I didn’t notice any color tints or weird hues, and upon measuring the display, found the white temperature to be almost exactly 6600K, very close to our 6500K target for calibration. This is nice to see out of the box. For gamers interested in ballpark color reproduction but not professonal level absolute colormetric reproduction, this is adequate.

Moving on, at 200 nits the VG236H gets a bit more accurate, down to 1.66, but still isn’t quite as good as an IPS panel. Still, not bad for a TN. Going down to 100 nits, we get a bit better, moving down to 1.61, but still not that elusive sub 1.0 the highest quality displays can deliver. What about gamut?

As expected, gamut is right around where we’d expect it to be for the TN, sRGB display. Interestingly enough, the OSD controls do have an sRGB mode, though I don’t think it’s as necessary as it would be on say a wide gamut display. But it’s there for certain.
 

NVIDIA 3D Vision - Part 2 Analysis: Color Uniformity
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  • MLSCrow - Monday, December 6, 2010 - link

    Though, I understand that 240Hz displays may not have been available or as available in August compared to now (December).

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