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The question of variable brightness comes more into play when HDR content is considered. The Q27G4ZD doesn’t have that feature but it manages some beautiful HDR anyway. It can emulate with three modes and when HDR10 content is present, there are two more dedicated presets.
HDR Brightness and Contrast
The XG272-2K is one of the brightest OLEDs I’ve tested at almost 1,000 nits peak. The next three all have variable brightness so they top 400 nits when measuring a 25% window. The two AOCs don’t have it and peak at the same level as SDR, just over 250 nits. While their highlights are not as impactful, the picture is still very textured and lifelike thanks to infinite black levels and contrast. The two HDR-specific modes, Display and Peak, have different luminance curves which I’ll show you below. Though the word Peak implies higher output, that is not the case. The Q27G4ZD measured the same in both modes.
Grayscale, EOTF and Color
The Q27G4ZD’s first two EOTF charts show the difference between Display and Peak HDR. Peak lowers light levels below 70% to make highlights pop more. It produces the desired effect, but some shadow detail is lost in the process. The better choice is Display, which shows all the detail found in the original content. Grayscale tracking is a tad warm but not enough that the image is negatively impacted. Go with Display and you’ll enjoy excellent performance.
In the color test, I noted some undersaturation in levels above 50% red and green. This is something that could be addressed in a firmware update. In content, HDR color looks fine in darker content, but brighter scenes have just a little less verve. This is relative to other OLEDs because the Q27G4ZD will still outperform all but the most premium Mini LED monitors with HDR content. Similar behavior can be seen in the BT.2020 test, but it still delivers good color for content mastered to that gamut.
Test Takeaway: The Q27G4ZD lacks a variable brightness feature which puts it behind most of the competition for peak output. And the red and green primaries are a bit undersaturated. But in practice, it still delivers excellent HDR, just not quite up to its full potential.
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