Calibrated Performance: Color Accuracy And Gamut

As ColorEyes Display Pro explains, absolute rendering the black point produces the most numerically accurate results; this 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 monitor. If matching two displays 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 monitors, but they add another variable to consider when judging color performance.

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. However, calibration changes color perception as colors become more accurately represented.

Unlike most IPS-based displays, we're unable to achieve an average delta E below 3 with the U2412M. That's really a symptom of its cheaper e-IPS panel, which forgoes many of the color filtering technologies present in H-IPS and p-IPS in order to drive down cost. Surprisingly, Acer's S242HL bid can hit a low delta E, but this doesn't help shore up the poor contrast ratio.

After calibration, we evaluate the profile against a GretagMacBeth's color palette.

As mentioned earlier, delta E is a measure of color accuracy. But it 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.

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

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). Rather, it's an absolute comparison of gamut volumes, which can be used to help identify strong and weak points in a color profile.

Once we inspect the 3D color gamut, the differences become clear. The U2412M does relatively well in blue and yellow production, but it's outperformed by the S242HL and T24A550 in these two specific regions. Instead, the U2412M's e-IPS panel is strong in blues, cyans, and greens at all levels. As we look to red production, the U2412M does only well in highlights, while the TN-based S242HL bid and T24A550 excel in rendering midtones and shadows.