HDR Grayscale, EOTF & Color
To run HDR benchmarks, we add an HD Fury Integral to the signal chain to simulate HDR10 content from our Accupel DVG-5000 pattern generator. This enables us to measure the CHG90's grayscale in 5% increments, track Electro-Optical Transfer Function (EOTF), an electronic value in content that specifies brightness displayed on the monitor, and calculate color gamut capabilities within a Rec.2020 container.
Grayscale Tracking & EOTF
Given the contrast results recorded, we had high expectations for EOTF accuracy. The CHG90 did not disappoint. Luminance ran slightly light, but that error didn't detract from this panel’s high contrast. Samsung’s zone-dimming edge backlight worked really well here. The green errors in the mid-tones were not too bad when viewing actual content. Our RGB chart includes luminance errors, so it’s not quite as grievous as the measurements make it look. Viewing a grayscale step pattern didn't reveal any concern-worthy issues. It is unfortunate though that the color controls are grayed out. Being able to calibrate grayscale would enable an improvement.
Color Gamuts Within Rec.2020
The CHG90 has the best color tracking we’ve seen thus far from any HDR monitor. Starting with the Rec.2020 chart, you can see that it hit all the inner targets until running out of available color. It approximated 100% saturation by altering hue towards the perimeter of the triangle. This is a technique used by many extended color displays.
The DCI and Rec.709 charts are near-perfect as well. It’s important to address accuracy here because you will find most content mastered in UHD will have been created on a DCI-P3 monitor. And in some cases, transfer teams still use Rec.709 along with HDR and UHD resolution. Since there are many interpretations of the standard, a monitor must be flexible and able to adapt. The CHG90 is the best example we’ve seen yet.
Ultra HD Blu-rays
We encountered a few challenges when watching movies on this monitor. On the plus side, it accepted a full-resolution signal from our Philips BDP-7501 UHD Blu-ray player.The monitor supported both 60 and 24Hz frame rates, and both HDR and extended color found on our copies of Creed and The Martian worked just fine. The flaw is that there are no aspect ratio modes that will properly show cinemascope content. The 2.4 aspect ratio is common on Blu-ray and UHD Blu-ray, but it this display (and every other ultra-wide monitor we’ve tested), lacks a vertical stretch mode. Without it, you can’t eliminate the black bars encoded into the top and bottom of the image. Furthermore, the CHG90 does not have a 21:9 option among its aspect choices. You can simulate several sizes of 16:9 and 16:10 images, but that is all.
It would seem that an AV-oriented source component is not the best choice for viewing video content here. You could achieve better quality with streaming software, which allows you to watch in a sizeable window. That way, you could use maximum screen real estate without distorting the image.
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