Calibrated Performance: Color Accuracy And Gamut

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 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.

All of three of the 22” LCD monitors struggle with rendering an absolute black, though. LG’s E2241V is the worst because it cannot seem to produce deep blacks at all. The calibrated black point is more than double that of the S22A350H, which is very telling given that Samsung’s S22A350H isn’t all that great either.

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, when you calibrate a monitor, 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.

After calibration, we evaluated the profile against a GretagMacBeth's color palette. As we mentioned earlier, delta E is a measure of color accuracy. However, this only gives a small representation of color performance since 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 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 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. When you compare in absolute terms, each monitor has its own strengths.

The Samsung S22A350H is surprisingly good at producing red midtones, even a few outside the AdobeRGB gamut. However, it suffers slightly in yellow and greens.

Dell's SR2220L does well at producing yellows, and it exceeds at producing blues out of the AdobeRGB gamut. Unfortunately, it performs rather poorly in red and greens.

LG's E2241V takes more middle-road approach. It does well in greens, but it suffers in red production (particularly near the highlights). This tends to compress the perception of red hues, as red highlights now appear as midtones. However, there's a cascade effect because midtones appear as shadows, which in turn look closer to black.

Notice that all three monitors perform strongly in yellow and blue tones. These are the fairly easy points to hit with today's LED-backlit TN-based panels. Often you see a strong blue bias caused by some lower-quality LED lights. This is what we see from the Dell and LG monitors. When you inspect the 3D map, you can see the shifted performance of the color gamut. If you are dead-set on matching the white point on multiple monitors or highly accurate color representation, this can be unsettling. However, as a practical issue, it shouldn't deter you from purchasing one of them.