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HDR Performance

Our HDR benchmarking uses Portrait Displays’ Calman software. To learn about our HDR testing, see our breakdown of how we test PC monitors.

The Q27G4ZMN is rated for DisplayHDR 1000 which makes it much brighter than most OLEDs. This is the principal advantage of Mini LED, which is further enhanced here by 1,152 dimming zones and a VA panel with high native contrast.

HDR Brightness and Contrast

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AOC Q27G4ZMN — (Image credit: Tom's Hardware)

The Q27G4ZMN is one of the brightest HDR monitors I’ve ever reviewed, coming close to 1,500 nits peak. And that is from a full-field white pattern. Windows maintain the same brightness, even when Local Dimming is set to Strong. That option affects black levels in a positive way, making them almost unmeasurable. 0.0128 nit is at the lower limit of my meter’s capability. It’s hard to compare the Q27G4ZMN’s 114,338.5:1 to the Xiaomi because that monitor simply shuts off its backlight. The AOC keeps it on at an extremely low level. In practice, you won’t see a difference between them. This is exceptional LCD performance.

Grayscale, EOTF and Color

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The Q27G4ZMN’s four HDR modes have slightly different luminance curves. Display is the best choice because it comes closest to the reference line. It’s a tad dark from zero to 50%, then it gets above the line. These errors are small and will not have a negative impact. Grayscale tracking goes a bit warm in the brightness steps above 70%. This too will be hard to spot in content.

The Q27G4ZMN’s HDR color is very oversaturated with its points anywhere from 5-20% past their targets. The progression is linear which maintains good balance, but you’ll see very vivid color in HDR content. I doubt most users will complain but it would be nice to have a mode that’s closer to the reference. Hue tracking is excellent for all six colors. The BT.2020 chart shows the same oversaturation with color topping out at 90% red, 75% green and 95% blue.

Test Takeaway: The Q27G4ZMN has excellent grayscale and EOTF tracking in all its HDR modes with Display being the best choice. Color is very oversaturated, not in a bad way, but there’s no perfectly accurate mode. Few users will complain about this as the picture is very bright and vividly detailed.

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Christian Eberle is a Contributing Editor for Tom's Hardware US. He's a veteran reviewer of A/V equipment, specializing in monitors. Christian began his obsession with tech when he built his first PC in 1991, a 286 running DOS 3.0 at a blazing 12MHz. In 2006, he undertook training from the Imaging Science Foundation in video calibration and testing and thus started a passion for precise imaging that persists to this day. He is also a professional musician with a degree from the New England Conservatory as a classical bassoonist which he used to good effect as a performer with the West Point Army Band from 1987 to 2013. He enjoys watching movies and listening to high-end audio in his custom-built home theater and can be seen riding trails near his home on a race-ready ICE VTX recumbent trike. Christian enjoys the endless summer in Florida where he lives with his wife and Chihuahua and plays with orchestras around the state.