Brightness And Contrast
To read about our monitor tests in-depth, please check out Display Testing Explained: How We Test Monitors and TVs. Brightness and Contrast testing is covered on page two.
ASUS MG278Q
Asus MG279Q
Asus ROG Swift PG279Q
Uncalibrated – Maximum Backlight Level
We've reviewed so many adaptive-refresh monitors over the past 18 months that it was difficult to decide which ones to include in the comparison group. Since the PG279Q is a premium product, that's the direction we went. All the screens here are 27-inch QHD panels with either G-Sync or FreeSync, representing IPS and TN technology. From last year we have the previous ROG Swift PG278Q plus Asus' two FreeSync displays, the MG278Q and MG279Q. Completing the round-up are Acer's XG270HU and XB270HU gaming displays. All are priced at the high end but FreeSync will save you around $200 at the same size and resolution.
There's no shortage of light output from any of the monitors but you can see what a difference the backlight strobing of ULMB makes. This is a 67 percent reduction and that's with both Brightness and Pulse Width at their maximums. Dropping the PW for greater blur-reduction makes the picture even darker.
The reduction in black level is about the same in ULMB mode, which means that contrast isn't affected too greatly. Compared to the rest, the PG279Q comes in mid-pack for blacks. It's a decent panel but the MG279Q and XB270HU are a little better.
Max contrast just cracks the 1000:1 level we look for. One caveat though—this is at the Contrast slider's default setting, which clips detail and reduces gamma accuracy. We'll see how calibration affects the final outcome below.
Uncalibrated – Minimum Backlight Level
Turning Brightness down to zero yields a 61.2828cd/m2 white level. It isn't quite at our preferred 50cd/m2 point but it's close enough for good image quality and gameplay in a completely dark room. The MG278Q and XB270HU are pretty much unusable at their minimum settings.
The PG279Q's minimum black level is consistent with the results we've recorded so far. The only way to do any better is with an AMVA display like the BenQ XR3501, but that means giving up both vertical resolution and adaptive refresh.
This represents very consistent contrast performance through the entire range of the backlight. But as we said above, there are bright-level detail issues associated with an incorrectly set contrast slider. We'll see how the fix affects the results now.
After Calibration to 200cd/m2
After calibration, the PG279Q retains its third-place standing in the black level test. The adjustment doesn't seem to affect the quality of low-end image detail.
We thought reducing the Contrast slider eight steps would kill the contrast ratio but it has only come down a small amount to our great relief. The drop is a mere seven percent, which is not much at all. What is obvious is the huge improvement in highlight detail and mid-range color saturation. The best IPS gaming monitors are based on the part shared by the MG279Q and XB270HU but the PG279Q isn't too far behind. So you aren't giving up any image quality to go with G-Sync and a super-high refresh rate.
ANSI Contrast Ratio
ANSI contrast is affected by a panel's uniformity, hence the lower result here. We could see slight hotspots at the upper-left and lower-right portions of our PG279Q sample. It doesn't impact most content but in very dark material, those corners look a bit washed-out.