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Our HDR benchmarking uses Portrait Displays’ Calman software. To learn about our HDR testing, see our breakdown of how we test PC monitors.
The XG27ACS offers excellent HDR performance for its class with high brightness, decent contrast and the same accuracy I measured in the SDR tests. HDR10 signals switch it over automatically where you get three additional picture modes and adjustable output if you so desire.
HDR Brightness and Contrast
With over 472 nits peak, the XG27ACS delivers a bright and tactile HDR image. Dynamic contrast is active as a field dimming feature, so contrast improves over SDR to 4,590:1. That beats the VA-based Lenovo in this test. Upon visual observation, the Asus looks better as well, mainly thanks to its greater output. I ran these tests in the Gaming HDR mode which is the default and best choice. If you find it too bright (I didn’t), you can turn on the brightness slider and dial down the fun a bit. This will also dial down the impact of HDR content since the luminance curve is altered from spec.
Grayscale, EOTF and Color
The XG27ACS generates some impressive HDR grayscale, EOTF and gamut results. There are no visible errors in grayscale whatsoever. The EOTF tracks to the reference and transitions to tone-mapping at around 70%. This is the correct point for the measured black and white levels. In the gamut tests, you can see some over-saturation which is typical for the HDR monitors I’ve tested. The points are linear and follow their hue targets so visually, there is nothing amiss. Rec.2020 content also renders at the same level of accuracy.
Test Takeaway: If you want the very best HDR, Mini LED or OLED is a better choice, but it will cost you a lot more than the $300 Asus wants for an XG27ACS. At that price, you’ll have difficulty finding better HDR. There is plenty of brightness, contrast is as good as any VA panel, and it is very accurate.
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