Grayscale, Gamma & Color
The C4008VU8 comes set to its Standard picture mode and Warm color temp preset. That locks you into the DCI-P3 color gamut, which is fine for most applications. We tested the sRGB option in addition to evaluate the monitor’s accuracy in a more common gamut.
Our grayscale and gamma tests are described in detail here.
Standard mode with Warm color temp measures well out of the box except for the 90 and 100% levels, which are too blue. In actual content, the error is barely visible, so the C4008VU8 can easily be used without calibration. The only drawback is that you’re locked into the DCI-P3 color gamut, which is significantly more saturated than sRGB. For most content, it looks fine, but if you seek accuracy, the only option is to select sRGB from the color temp menu. That reigns in the gamut, but whites become very warm with errors across the board. The average value is 7.8dE and brightness is locked at 185cd/m2.
When we calibrated in the user color temp, we got roughly the same numbers as Warm. Blue errors have been reduced, but some red has crept into the lower steps. The visual result is almost indistinguishable. We suspect most users will simply leave their settings alone and adjust brightness to taste, and that produces a very good image.
You can see our calibration did not produce any gain in accuracy. While 1.71 and 1.74dE are decent numbers, the other screens are capable of better. Since the sRGB preset has a high 7.8dE average error, we don’t recommend it. Our preference was to accept the wider DCI-P3 gamut and leave the User color temp at its calibrated settings.
Regardless of other settings, the C4008VU8 offers the same consistent gamma tracking in the number one preset. In Standard, before and after calibration, the trace hugs the line until 90% where there is a small but invisible dip, corresponding to a rise in luminance. The sRGB preset trades that for a dip at 10%. That will bring out some shadow detail, but again, it’s a barely noticeable error. If you decide to calibrate the RGB sliders, you must reduce Contrast by at least 10 clicks to reproduce our results.
All the displays have tight gamma tracking near the 2.2 mark except the XB321HK, which runs a little dark. Visually, there is little difference, but the C4008VU8’s higher contrast means much greater image depth and a picture that looks sharper and more three-dimensional.
Color Gamut & Luminance
For details on our color gamut testing and volume calculations, please click here.
In the first chart, it’s easy to see the C4008VU8’s extended color gamut. AOC has wisely kept luminance levels near-neutral, which means the overall errors are low. Without adjustment, the average DeltaE is just 2.26. And if you look at each color, only red is significantly over-saturated. Green and blue are much closer to the mark. Plus, tracking stays close to target until the gamut’s limit is reached.
If you need an accurate sRGB gamut, the sRGB color temp mode delivers. It’s too bad it won’t render the same accuracy in grayscale tracking, which is quite warm. This is what we meant by compromise when calibrating. You can’t quite have it all with this monitor. But if DCI-P3 is what you’re after, it’s one of the only displays out there that can nail it perfectly. The last two charts show our measurements against that standard. The error falls to just 1.88dE then, better than the sRGB value. That makes the C4008VU8 a great display for Ultra HD Blu-ray since those discs are mastered with extended color.
2.14dE is a perfectly respectable result, but it isn’t up to the capabilities of the other monitors here because they are strictly sRGB screens. That AOC can make a DCI-P3 display work well for sRGB/Rec.709 content is a testament to engineering and compromise. Extra color saturation can often make the picture look artificial and over-blown, but the C4008VU8 doesn’t suffer from that problem.
Since sRGB volume is well over 100%, we recommend a custom profile if you plan to proof material on this monitor. We also calculated DCI-P3 volume and came up with a 94.32% result. That is due to a slight under-saturation in the green primary.
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