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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 GM27-FQS gives the user a few more options in HDR mode than most monitors. There are three picture modes: Game, Movie and Standard. All three let you adjust brightness and contrast, and Standard adds black level, white level and RGB sliders.
HDR Brightness and Contrast
The default HDR mode is Movie, and it has very accurate grayscale tracking with no visible errors. EOTF luminance tracking is a little dark, and I noticed some slight clipping of shadow detail. The Game mode measures identically. The Standard mode looks the same but adds some adjustments. A control called Lightness raises the black level, and it is possible to adjust it to where the EOTF tracks perfectly. But this flattens the picture because there is no dynamic contrast in operation. You can see that though there is output over 325 nits, contrast is exactly the same as it is for SDR content. I don’t recommend adjusting the Standard HDR mode for this reason. It actually looks better in Movie or Game with slightly darker blacks which increase perceived contrast.
Grayscale, EOTF and Color
The first chart shows what I’m talking about concerning the Movie mode’s EOTF. With darker levels up to the 55% tone-map transition, the low and mid-tone shades are indeed darker, but this is a good thing, given that the GM27-FQS has no dynamic contrast. Some detail might be a little harder to see, but most content looks fine. However, it isn’t significantly different from SDR.
Color tracks its hue targets well in both DCI-P3 and Rec.2020-mastered content. Red and blue is a little over-saturated but not to the point where detail is obscured. Magenta is a little off in hue as well. Despite the promise of the Rec.2020 mode in the Color Space menu, the GM27-FQS is a DCI-P3 monitor. It tracks the 2020 targets properly until it hits the color limits around 80%. This is very good performance.
