Results: Viewing Angle And Uniformity
Since this is an IPS-based panel, we expect to see excellent off-axis viewing performance. Unfortunately, the GB-r-LED backlight seems to have a slightly negative effect on this.
The result we observe is a little unexpected. There is a slight red shift from side to side, and a slight blue shift from top to bottom. It’s subtle to be sure, but it is there. We can only theorize that this is a product of the PA279Q’s unusual two-color LED backlight. Since all of the light coming from an LCD panel is polarized, it follows that two different wavelengths emanating from the screen will shift differently as the viewing angle increases. There is no LCD panel that looks perfect in this test, which is part of why Asus bundles a hood with the PA279Q. To properly judge color on this or any panel, you need to be sitting front-and-center.
To measure screen uniformity, zero-percent and 100-percent full-field patterns are used, and nine points are sampled. In a change from previous reviews, we compare the results to other monitors we’ve measured. First, we establish a baseline measurement at the center of each screen. Then the surrounding eight points are measured and their values expressed as a percentage of the baseline, either above or below. This number gets averaged. It is important to remember that we only test the review sample each vendor submits. Other examples of the same monitor can measure differently in this metric.
Since the PA279Q has a uniformity compensation option, we measured the monitor both ways. This option is not available in the sRGB or Adobe RGB modes, only in Standard or User.
First up is black field uniformity.
This number represents the sRGB mode, so compensation is not active. When we switch to a calibrated User mode and turn that feature on, the black field uniformity improves to 8.39 percent. However, black level increases as well. We feel the gain in uniformity isn’t worth a visible rise in black level.
Here’s the white field measurement, again in the sRGB mode.
This is another excellent result. When you switch to User mode and turn compensation on, the percentage drops to 3.40. But the white level increases too, necessitating a brightness control adjustment. After experimenting with all of the available options, we still feel the fixed sRGB and Adobe RGB modes are the way to go.
Screen Uniformity: Color
Starting with our review of AOC's Q2963PM, we added a new uniformity test to our benchmark suite: color. The above measurements only address luminance. Now we’re measuring the white balance variation in an 80-percent white field pattern. The results are expressed as a variation in Delta E (in other words, the difference between the highest and lowest values). We didn’t perform this test on the Samsung S27B970D, so we can’t include it here.
With a variance of only .40 Delta E, the color variation across the screen is essentially nil. This is another important metric for any pro-level monitor and the PA279Q certainly qualifies. If you’re curious about the effect of the uniformity compensation feature, our result was an incredible .08 Delta E variation! It’s too bad this option isn’t available in sRGB or Adobe RGB mode.
