Grayscale, Gamma and Color
We measured the 34GK950F in three modes, Gamer 1 (the default), sRGB and Gamer 1 calibrated. If you want sRGB color, you must choose that mode. Otherwise, all content will be rendered in the DCI-P3 color space whether its SDR or HDR.
Grayscale and Gamma Tracking
We describe our grayscale and gamma tests in detail here.
In the default Gamer 1 picture mode, the 34GK950F rides on the edge of needing a calibration. It’s likely some samples will measure better than others, but ours was acceptably accurate. With a slightly cool tint, content looked a bit flat. The spike at 100 percent is due to clipping of red detail. Gamma runs close to the 2.2 line, except for the brighter steps from 80 to 100 percent. Usually a reduction in the contrast slider can fix this.
The best fire-and-forget mode is sRGB (second graph). Grayscale is comfortably beneath the threshold of visible error, and gamma is spot-on. If you prefer the extra color of the other modes, this mode isn’t for you. But it is very accurate for SDR games and video content. The average error of 2.34dE matches the included factory calibration data sheet.
Calibration of the Gamer 1 mode (third graph) produced excellent grayscale tracking, but the gamma dip at 80 and 90 percent was still there. In actual content, some highlights had subtle detail clipping, but the overall effect was subtle. The simplest approach is to leave the 34GK950F on Gamer 1 for all content unless you prefer a more accurate sRGB gamut for SDR material.
With a 3.11dE average grayscale error, most users will not see a need to calibrate the 34GK950F. We always try to extract maximum performance from our review monitors, so our calibrations (second graph) yielded a nice gain to a mere .95dE average.
We found the best gamma in sRGB mode, where it tracks the 2.2 spec to perfection. In Gamer 1 mode, where the color gamut is wider, luminance accuracy was a little lower with a 0.44 range of values and a 5 percent deviation from standard. This is acceptable performance, but there is room for improvement.
Color Gamut Accuracy
For details on our color gamut testing and volume calculations, click here.
The 34GK950F is a native DCI-P3 monitor for both SDR and HDR content. In the default Gamer 1 mode (first graph), it tracks the saturation and hue targets very well with slight deviations in cyan and magenta. We easily corrected these with grayscale calibration. Saturations are on or near target, despite the gamma error we recorded at 80 and 90 percent brightness. This is excellent out-of-the-box performance.
The sRGB gamut (second graph) tracks even better, with a super-low average error of 1.3dE. It doesn’t get much better, and that puts the 34GK950F on par with many professional monitors. If you need accuracy for color-critical work, this display can deliver.
Calibration (third graph) tightened up all hue and saturation measurements, putting every dot within the target box. The resulting average error was, again, equal to or better than some professional screens. With calibration, the 34GK950F can be used as a DCI reference monitor.
The 34GK950F competes favorably with the best gaming monitors in both sRGB and DCI-P3 color accuracy. It’s perfectly acceptable without calibration, but making a few adjustments took the monitor to a high level and is well-worth the effort. It should be noted that the PG27U and VP3881 are factory-certified for color accuracy and cost more than the LG.
The 34GK950F also covers more of the DCI-P3 gamut than almost every other HDR monitor we’ve reviewed. That KSF phosphor backlight is effective in extending color without significantly increasing cost or power consumption. Only a slight green deficiency prevents it from covering more volume. In sRGB mode, the blue and red primaries were also a tiny bit undersaturated.
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