Feeding the CP7271K an HDR signal automatically put the monitor in HDR mode and grayed out most image controls. One option that remained available is the zone-dimming response, which has three options. We found Gaming to come closest to spec and provide the best image, with no detail clipping and deep contrast.
HDR Brightness and Contrast
Since the zone dimming feature is dynamic, we waited a few seconds for our 100% white pattern to stabilize before recording an impressive 1,180.5381 nits. Black levels are difficult to measure, but we were able to record a 0.0268 value, which results in an HDR contrast ratio of 44,095.2:1. While impressive, it’s surprisingly low in this comparison. Will you actually spot the difference between 44,000:1 and 60,000:1? Probably not. The PA32UCX, however, is on another level, and you’ll see that difference for sure. It remains our benchmark for 4K image quality.
Grayscale, EOTF and Color
The CP7271K’s grayscale and color accuracy in HDR mode is quite good. The tone-mapping point determined by white and black level measurements is at 75%, which the monitor reached a bit early due to its zone dimming feature. We measured all three response options, and Gaming proved closest to correct. What our measured EOTF shows is that some highlight details may be slightly obscured in rare circumstances. We didn’t see any issues during hands-on testing. Grayscale tracking was also right on the mark.
Color tracking in HDR mode is very good with only slight oversaturations in all six colors. Ultra HD material looked very well-saturated with natural and accurate hues throughout the brightness range. Rec.2020 also tracks well up to the point, where the CP7271K runs out of color. This is as it should be. Monitors will have full 2020 coverage someday, but today is not that day. Acer’s ConceptD provides reference-level HDR accuracy and performance.
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