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.
We approached the PA279Q a little differently than other screens we’ve reviewed due to its greater number of calibration options. Here is our baseline measurement of the Standard mode at default settings.
In Standard mode, you can adjust the color temperature preset, but not the RGB sliders. The default option is 6500 K. But as you can see, it runs a little too red. The error becomes visible at 40 percent brightness and above. Setting the PA279Q to the 9300 K option causes a slight blue tint to the white parts of the image.
There are two ways to improve the grayscale. One is to configure the User modes, which allow custom tailoring of both grayscale and color (though not without penalties, as you’ll see in the color section of the review). If you do that, you’ll be rewarded with excellent results.
It doesn’t really get better than this. Check out the 60-percent brightness level, which has a Delta E error of only .14! If you choose to use the like that, be sure to check out our color results on page seven first.
The compromise is to be found in the sRGB and Adobe RGB modes.
This is a pretty good chart, calibrated or not. Asus advertises a high degree of accuracy for the PA279Q and it certainly delivers on that promise. Visible errors don’t occur until 90 percent brightness, and then only barely. You get the exact same results in the Adobe RGB mode.
Let’s bring our comparison group back into the mix. Since we chose sRGB as the best all-around picture mode, the numbers below represent that mode.
The stock number is quite good, bested only by HP's E271i. Even the factory-calibrated Samsung S27B970D isn’t quite as good, yielding a stock error of 2.56 Delta E. We’re picking nits, but the PA279Q does undercut that screen’s price by almost $300.
Since we couldn’t adjust grayscale in sRGB mode, the final number doesn’t change much.
The other displays rank higher by virtue of their available RGB adjustments. But the PA279Q still comes in well under the visible error level of three. If you employ User mode, you can get the average Delta E down to .71 which ties the Samsung for lowest grayscale error we’ve measured. It’s unfortunate that the color gamut is not as accurate in the User modes.
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.
Again, this is the sRGB mode. However, this gamma result is nearly identical to the Standard, User, and Adobe RGB modes. The tracking is fairly flat and rides just below 2.2. The maximum error here is less than 4 cd/m2.
Here’s our test group again for the gamma comparisons.
Asus' PA279Q is among the very best for gamma tracking. This level of consistency is only present in three other monitors we’ve tested this year. The S27B970D is exceptional, and Asus trails it by only a tiny bit.
We calculate gamma deviation by simply expressing the difference from 2.2 as a percentage.
The five-percent deviation from 2.2 is fairly small, representing no more than 4 cd/m2. Again, the PA279Q is among the best screens we’ve measured for gamma performance.
