Results: 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.
Uncalibrated – Maximum Backlight Level
The PN-K321 is the sixth Ultra HD monitor we’ve reviewed, so we have a perfect lineup of 4K-only screens in our comparison group. IGZO is represented by Asus’ PQ321Q and Dell’s UP3214Q. Also from Dell is the UP2414Q, a 24-inch IPS-based display. Finally, we’re including two 28-inch TN monitors: Dell’s P2815Q and Asus’ PB287Q. If you’re shopping for 4K, this should be a great help to your research.
The PN-K321 is the brightest 4K screen we’ve measured so far. It’s rated at 350cd/m2, but easily exceeds that figure. With so much screen area, it'll light up your office, even at half-brightness. There’s plenty of output available for use outdoors, on location.
With the backlight set to its maximum, the black level is a bit higher than most of the competition. It is lower than Asus' screen though, which uses the exact same panel part.
At 808.5 to 1, the PN-K321’s contrast is a little disappointing. We’d like to see at least 1000 to 1, and we know it’s possible since Dell's offering records a 1004.4 to 1 result.
Uncalibrated – Minimum Backlight Level
At the minimum setting, Sharp's PN-K321 settles at a near-perfect 56.1158cd/m2. It yields a perfectly usable image if your office is dark and the contrast level only drops by a hair.
The minimum black level is still a bit high among our group, but not relative to the white level. A result of .0705cd/m2 is pretty dark. At this setting, you need to turn the lights out to see full shadow detail.
The minimum contrast ratio is pretty close to the maximum one, indicating consistent performance. We’d like to see a higher number across the board, but we believe the majority of users will be satisfied with Sharp’s image quality.
After Calibration to 200cd/m2
The calibrated black level is still at the back of the pack, right behind the PQ321Q. Dialing in the grayscale, something we feel the PN-K321 requires, will harm this result just a bit.
After grayscale calibration, contrast diminishes by almost 15 percent partially because the RGB sliders start at their maximum settings (at least for the high range). In general, however, this particular panel doesn’t match the contrast performance of its competitors; most notably the wide-gamut part used in Dell's UP3214Q. If Sharp is to maintain its higher price point, the company might consider using that screen in its next-gen product while keeping the cost similar or lower.
ANSI Contrast Ratio
ANSI results are at least consistent, if not surprising at only .08 percent below the on/off figure. There’s no question that the PN-K321 sports high build quality and solid performance.