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Grayscale, Gamma and Color
The easiest way to enjoy the X27 is right out of the box. Its sRGB and HDR color accuracy are quite good with no need for adjustment. However, we delved into the OSD to satisfy our tweaker urge and found some small gains.
Grayscale & Gamma Tracking
Our grayscale and gamma tests are described in detail here.
The X27’s grayscale and gamma charts show no visible errors. There was a slight uptick to blue at 50 percent brightness and above, and gamma showed a small dip at 10 percent, but none of these pose an issue in actual use. This is professional-level performance all the way.
Turning SDR sRGB Color off created a few visible errors in grayscale tracking. The blue tint can be seen from 70 to 100 percent brightness. It’s a minor issue, and most users will probably enjoy the larger color gamut, even if it isn’t the most accurate way to use the display.
Calibration reduced the grayscale error to just .67dE average but lightened gamma slightly. The difference was hardly noticeable to our eyes, but we wish the gamma presets were a little closer together. We tried setting it one click darker but that took the average gamma value well over 2.4, which is much too dark for SDR content.
Comparisons
By default, the X27’s grayscale error is just 1.2dE, easily winning the out-of-box comparison.
After calibration, all the monitors boasted reference-level performance. We didn’t include the Dell here as we weren’t able to use its software to make adjustments at the time of the review, and it isn’t designed for OSD adjustments.
The X27 has very tight gamma tracking, resulting in a small .14 range of values. But it rode a bit below the 2.2 standard, placing it last in our deviation test. Once we turned the variable backlight feature on, these issues became hard to spot, so it’s far from a deal-breaker.
Color Gamut Accuracy
For details on our color gamut testing and volume calculations, click here.
The X27 tracked the sRGB spec very well, with some slight under-saturation in red. There were also hue errors in cyan and magenta, but this was easily solved with calibration.
Turning off SDR sRGB Color produced an interesting result. Acer advertises Adobe RGB as the X27’s native gamut, but there was far too much red for that to be the case. We compared it to the DCI-P3 spec instead and came closer to the design intent. The only place we could see an issue was the green primary, which didn’t quite meet its hue targets. There was plenty of saturation here though, which made for a vivid and bright image. If you choose to use the X27 this way for SDR content, you’ll enjoy the extra color, even if it isn’t quite accurate.
Comparisons
In sRGB mode, the X27 was without fault. A .88dE score is about as low as it gets. Only the Asus PG27U can do better, and in that battle, only a meter can tell the difference. This is some seriously accurate color. The green primary skewed the DCI score somewhat, though 3.32dE isn’t too far off the mark; anything under three is considered an invisible error.
With Ultra HD and HDR, DCI-P3 color is an important spec, and the X27 rendered over 88 percent of that gamut. That’s a mid-pack finish here, but it exceeds many of the other extended-color monitors we’ve reviewed over the past year. sRGB volume cane up a tad short of 100 percent, thanks to a slightly undersaturated red primary.
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