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Asus PQ321Q 4K Monitor Review: Top-Shelf Ultra HD For $3500

Results: Viewing Angles And Uniformity

Each flavor of LCD technology brings a different off-axis viewing experience. Because the emitted light is polarized, there will always be some variation in either brightness, color, or both whether you're talking about TN, IPS, or in this case, IGZO. The type of backlight also affects the result.

Asus' PQ321Q demonstrates excellent performance in the vertical plane, while the horizontal shows a slight shift towards green. Luminance is preserved very well and detail holds up beautifully. We can see the darkest steps in all of the patterns without difficulty.

Screen Uniformity: Luminance

To measure screen uniformity, zero- and 100-percent full-field patterns are used, and nine points are sampled. In a change from previous reviews, we’re now comparing 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 sends us. Other examples of the same monitor can measure differently in this metric.

First up is black field uniformity.

We're shown yet another excellent result. We can’t see the variations reported by our meter. Looking at the individual measurements, the hot spots occur in the upper-left and lower-right portions of the screen. Increasingly, we're finding 10 percent to be a good standard by which to judge screen uniformity. Beyond that and you’ll likely see the hot spots; below 10, you won’t.

Here’s the white field measurement.

The PQ321Q turns in another excellent result. There are no visible variations in brightness anywhere on the screen. By the numbers, the center is actually brighter than the surrounding areas, except for bottom-center, which is the brightest of all. That's all according to our meter. Visually, it’s perfect.

Screen Uniformity: Color

To measure color uniformity, we display an 80-percent white field and measure the Delta E error of the same nine points on the screen. Then we subtract the lowest value from the highest to arrive at the result. A smaller number means a display is more uniform. Any value below three indicates a variation that is invisible to the naked eye.

Even though our measured result is nearly as high as Dell's P2714T, where we could just see the color shifts, we can’t see any white balance differences on the PQ321Q. The greatest error is in the top left at 3.04 Delta E. This barely just cracks the visibility point.

Christian Eberle is a Contributing Editor for Tom's Hardware US. He's a veteran reviewer of A/V equipment, specializing in monitors.