Results: Grayscale Tracking And Gamma Response
A 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.
The XL2720Z comes set to its FPS1 picture mode, so that’s where we begin our grayscale tests.
This is a fair result, but it could be better. The average error is 3.61 Delta E. Grayscale shifts toward blue as brightness increases. From 50 percent on up, you’re able to see a slight blue tint. Fortunately, you can adjust the RGB sliders in this mode (though you can’t change the gamma preset).
Standard is a better mode to use if you don’t plan to calibrate.
The Standard mode chart is pretty close to some of the professional screens we’ve tested, including those with factory calibrations. All errors are under three Delta E and therefore invisible. At this point, all you need to do is change the gamma preset to 4 and you have a very accurate monitor.
Of course, we aim for the top!
It doesn’t get much better than this. In fact the only monitor we’ve measured that beats the XL2720Z is Samsung's S27B971D. Many gamers don’t consider calibration to be important, but trust us, you’ll have a better experience using a more accurate screen. Flat and neutral grayscale tracking means maximum image depth, natural color, and minimal eye fatigue.
Here is our comparison group:
Grayscale performance in the XL2720Z’s stock configuration is very good. In fact, there are a couple of pricier screens below BenQ's display in the results. Remember, these charts represent the Standard picture mode. The FPS modes are not quite as accurate pre-calibration.
After adjustment, the BenQ comes out a winner.
Another trend we’re seeing in new monitors is near-perfect grayscale tracking after calibration. We only had to change the RGB sliders by a few clicks to achieve our best result. It also helps to reduce the contrast control a little. Trading a little on/off contrast for this level of accuracy is definitely worthwhile.
Gamma Response
Gamma is the measurement of luminance levels at every step in the brightness range from 0 to 100 percent. It's 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 used standard for television, film, and computer graphics production. The closer the white measurement trace comes to 2.2, the better.
The different picture modes of the XL2720Z produce varying gamma results. Correct gamma is important if you want to see maximum detail in a gaming environment.
The FPS1 mode yields a fair gamma result. It rides pretty close to 2.2 until 90 percent brightness, where it takes a dip below the line. We measure an error of 7.13 cd/m2.
But again, the Standard mode is preferred for its superior color gamut results, which you’ll see on the next page. Unfortunately, the gamma is not as good as FPS1.
This trace is well below 2.2 across the board, and it doesn’t track well. The maximum error is again at 90 percent, where the XL2720Z measures 12.46 cd/m2 too bright. The image definitely looks flatter with less pop and clarity.
The fix is an easy one.
All you have to do is change the gamma preset from 3 to 4 to bring the gamma tracking up to 2.2. It’s not the flattest tracking we’ve measured, but it comes close. Ninety percent is only off by 2.47 cd/m2; that's a negligible amount.
Here is our comparison group again:
The XL2720Z has some pretty stiff competition in this round-up and it still finishes in third place. A result of .14 represents tight gamma tracking.
We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.
Even though the BenQ is on the bottom of our test group, we have no issue with its gamma performance. Compared to the rest of our monitor benchmark database, the XL2720Z lands around the middle.
