Results: Grayscale Tracking And Gamma Response
The majority of monitors, especially newer models, display excellent grayscale tracking (even at stock settings). It’s important that the color of white be consistently neutral at all light levels from darkest to brightest. Grayscale performance impacts color accuracy with regard to the secondary colors: cyan, magenta, and yellow. Since computer monitors typically have no color or tint adjustment, accurate grayscale is key.
Because of the issue we discovered with the Contrast control, we feel Standard is the best mode to use, regardless of whether you calibrate or not. We also recommend the User color temperature preset, even if you don’t adjust it.
The VG248QE’s grayscale runs towards blue at every brightness level. All measurement points have visible errors. Fortunately, blue errors are the least detrimental to image quality. The white point error we really don’t want to see is green, and there’s obviously no problem there.
The tracking is fairly linear, so it should dial in well with calibration.
Aside from slight aberrations at 0, 10, and 100 percent brightness, this is an excellent chart and a significant improvement over the stock configuration. All the Delta E numbers are below two, except for 10 percent brightness. Forty through 80 are well under one.
Let’s bring our comparison group back into the mix.
The VG248QE is on the high side of average in this test. HP's E271i is exceptional, while the majority of monitors tested do have some visible grayscale error out of the box.
Things look much better after calibration.
At a Delta E of 1.3, Asus demonstrates excellent calibrated performance. Even the most particular gamers will be more than satisfied with the grayscale accuracy of this monitor. Speed isn't its only strength. Rather, Asus offers solid performance in all areas.
Gamma Response
Gamma is the measurement of luminance levels at every step in the brightness range from 0 to 100 percent. This is important because poor gamma can either crush detail at various points or wash it out, making the entire picture appear flat and dull. Correct gamma produces a more three-dimensional image, with a greater sense of depth and realism. Meanwhile, incorrect gamma can negatively affect image quality, even in monitors with high contrast ratios.
In the gamma charts below, the yellow line represents 2.2, which is the most widely accepted standard for television, film, and computer graphics production. The closer the white measurement trace comes to 2.2, the better.
The VG248QE doesn’t have a gamma control. But apparently it doesn’t need one. The measurement trace stays nice and flat until 90 percent brightness, where it takes a bit of a dip. This is a slight error, and is only 1.34 cd/m2 higher than the target value. One thing we noted during the testing: at higher brightness settings, the gamma dip at 90 percent increases a little. For the best gamma performance, you’ll want to stick to around 200 cd/m2 max output.
Here’s our test group again for the gamma comparisons.
At a value range of .35, the VG248QE is squarely in the middle of this pack, and also mid-pack among the screens we've tested this year. In short, gamma tracking is very good (well below the point where it negatively impacts image depth or detail).
We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.
A variation of 1.36 percent puts Asus in second place today, and fifth overall. Numbers like these mean the VG248QE has no gamma issues to speak of. It tracks a 2.2 value well as long as you work around a max brightness level of 200 cd/m2 or less.
