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Calibrated LCD Performance: Color Accuracy And Gamut

Touchscreen Computing: Gateway ZX4931 And HP TouchSmart 310

As ColorEyes Display Pro explains, absolute rendering the black point produces the most numerically accurate results, and works well for high-quality monitors. But doing so could also easily generate plugged shadows (dark regions where detail is lost) on a lower-quality display. If matching two screens is critical, absolute rendering is the best choice, assuming both monitors can handle absolute black. Relative rendering maps the darkest values on your monitor relative to its ability to display them. This isn't as accurate, but provides detail in dark areas where your monitor has difficulty.

Since we are trying to compare the color quality between monitors, we choose to calibrate for an absolute black point. These values represent the best we can achieve with our all-in-one PCs, but they add another variable to consider when judging color performance.

Once calibrated, HP's TouchSmart 310 is able to achieve much darker blacks, and we see little detail lost in the dark regions thanks to a high contrast ratio. We can't say the same for Gateway's ZX4931; it struggles to produce dark blacks. In the end, we have to settle for a higher calibrated black point and the loss of some detail.

Gateway One ZX4931Gateway One ZX4931HP TouchSmart 310HP TouchSmart 310

Gateway One ZX4931Gateway One ZX4931

The range of colors doesn't change when you calibrate a monitor (a wide-gamut monitor still behaves like a wide-gamut monitor, even when you turn down brightness). Rather, color perception changes as colors become more accurately represented. This is the result of changing the shape of the luminance curve on a gamut map.

We evaluated the calibrated profile of each all-in-one PC against a GretagMacBeth's color palette. As we mentioned earlier, delta E is a measure of color accuracy. HP continues to be weak near blue tones, but Gateway has surprisingly good color accuracy when it's compared against other similar LCD monitors. However, this only gives a small perspective of color performance because we interpret colors within a spectrum, not from individual points.

Absolute Color Gamut

It's harder to perceive the difference in gamut when you’re inspecting individual delta E values. With 3D images, it is best to examine the graph as a video, which is why we use Chromix's ColorThink Pro to illustrate how color gamut is affected.

Calibrated Color Gamut: Gateway One ZX4931

The wire form outline in each video represents the total gamut volume of AdobeRGB 1998. The solid gamut map represents the gamut of each monitor.

Calibrated Color Gamut: HP TouchSmart 310

Remember, this is not just an examination of how one color profile maps to a reference, nor is it only about how much can be rendered (in this case AdobeRGB 1998). This is an absolute comparison of gamut volumes, which can be used to help identify strong and weak points in a color profile.

HP's TouchSmart 310 generates much better highlights (bright tones) and shadows (dark tones) across almost the entire gamut. However, the ZX4931 has three strong points: it produces noticeably better blues and magentas, and slightly better greens. Provided you have a decent eye for color, you can actually see the difference in blue color production when these displays sit side by side.

Other differences are subtler, but the results are surprising nonetheless. Based on the 3D gamut map, HP performs extremely well in red production. It’s even able to produce a few red highlights outside AdobeRGB 1998. Yellow and blue tones are easy to hit with today's TN-based panels, but accurate green and red production is harder to achieve. With a larger red gamut, HP's TouchSmart 310 can provide a lot of vividness, especially if you are viewing high-contrast media.

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