Grayscale Tracking And Gamma Response
Our grayscale and gamma tests are described in detail here.
For a factory-certified monitor, the Z27q's default mode is surprisingly inaccurate. Custom RGB is the only mode that allows grayscale adjustments so it is possible to calibrate the color temperature to a proper D65, or any other value you may wish to try. The RGB sliders have 256 steps, which means you can specify a large variety of white points with precision.
In the fixed Adobe RGB mode, grayscale tracking is essentially perfect. Errors are all below two Delta E, which means they're invisible to the naked eye. Even though you can't perform a calibration in this mode, the brightness control is still available.
You can expect the same excellent performance in the sRGB preset. There are no problems to report here and you have the same access to the brightness slider.
Calibrating the Custom RGB mode yields another ideal chart. There are no errors to speak of here, however we did encounter some color gamut issues in this mode. Before deciding on the best picture mode, we recommend you check out our color test results on the next page.
Here is our comparison group.
In the factory-certified Adobe RGB and sRGB modes, the Z27q exhibits the grayscale performance expected from a premium professional product. Since there are no calibration options here we're repeating the same numbers for both the pre- and post-calibration comparisons.
With the exception of the Z27x, the other monitors here can be calibrated to slightly higher standards than their factory states. The PA322UHD shows the greatest improvement although any of these screens are perfectly usable without adjustment.
We measured the gamma in every picture mode and got the same result each time. Tracking is perfect except for a hump at the 10 percent level, which means that the brightness point is a little too dark. It doesn't affect image quality significantly but it might result in a loss of fine shadow detail.
Here is our comparison group again.
The Z27q's last-place finish is solely due to its error at the 10 percent brightness level. If not for that, it probably would have risen to the top spot.
We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.
That single error is also responsible for its average gamma value of 2.27. All other luminance points are within a hair of 2.2. This error does not affect the color saturation results, which we'll show you on the following page.