Brightness & 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.
Uncalibrated – Maximum Backlight Level
All of today’s comparison screens can run at 144Hz or higher and include either G-Sync or FreeSync adaptive refresh. They’re all TN panels except the AOC AG271QG. In addition to the PG258Q, we have Asus’ PG248Q, AOC’s AG271QX and G2460PF, and Dell’s S2417DG.
If you’re going to have a proper blur reduction implementation, you need extra output to compensate for the reduction caused by backlight strobing. Asus takes that mantra to a new level with over 470cd/m2 from the PG258Q. It’s spec’d at 400, so we’re glad to see the extra headroom. That means you can easily achieve 200cd/m2 in either G-Sync or ULMB modes. In fact, you can get nearly 300cd/m2 in the latter mode with the pulse width set to 100.
Obviously a bright backlight won’t help black levels, but the resulting sequential contrast just manages to crack 1000:1. Only the IPS-based AG271QH achieves a higher dynamic range. TN is not known for great contrast, so Asus is raising the bar here.
Uncalibrated – Minimum Backlight Level
That high output backlight also means minimum levels remain on the high side. If you turn off all the room lights, the PG258Q is a little bright for marathon gaming sessions. You can compensate by adding some interior lighting to your PC’s case. That extra bit of bias will help reduce fatigue when playing in the dark. Contrast remains consistent at 994.2:1.
After Calibration to 200cd/m2
We’re including the white level chart to show ULMB’s effects on output. It reduces light by 35% at maximum pulse width, which is typical for G-Sync screens in general. With the PG258Q’s extra output and independent brightness control, however, that reduction becomes a non-factor, especially when you notice there’s almost no visible difference in contrast. Asus has obviously responded to users who've asked for a more usable ULMB implementation. Past monitors required too much compromise in image quality. Here though, once you equalize the brightness setting, there’s no difference to speak of. And don’t forget that ULMB works up to 144Hz, another first for us.
ANSI Contrast Ratio
The PG258Q’s panel may be TN, but its quality stands above the rest. 990.8:1 is a fantastic ANSI result for any monitor that’s not VA. Asus has not skimped on quality here. Not only does intra-image contrast look amazing, the perceived quality is quite a bit higher than the rest. Image depth is easily on par with a good IPS screen. And you’ll see on page five that even its viewing angles are better than other TN screens.
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