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Results: Brightness And Contrast

Dell UltraSharp 24 Ultra HD Monitor: The $1300 UP2414Q
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Uncalibrated

Before calibrating any panel, we measure zero- and 100-percent signals at both ends of the brightness control range. This shows us how contrast is affected at the extremes of a monitor's luminance capability. We do not increase the contrast control past the clipping point. While doing this would increase a monitor’s light output, the brightest signal levels would not be visible, resulting in crushed highlight detail. Our numbers show the maximum light level possible with no clipping of the signal.

Our comparison group includes the last six monitors reviewed at Tom’s Hardware, including Asus' PQ321Q and Dell’s UP3214Q Ultra HD screens. Before we move on, all of the luminance measurements are taken with Uniformity Compensation turned off, except where noted otherwise. When it’s turned on, the monitor’s dynamic range is reduced by about 16 percent, mainly due to a higher black level. We used the fixed Adobe RGB picture mode for these tests.

Despite their significantly different panel technologies, the UP2414Q and UP3214Q post nearly-identical max brightness numbers. This looks to us like a decision on Dell’s part to keep its products consistent across the same model line. A result of 326 cd/m2 is more than enough light output for any conceivable room environment or computing task.

Let’s see where that high backlight setting puts the black level.

Unfortunately, .4287 cd/m2 is fairly high. You’ll see as we go on that the UP2414Q’s contrast performance isn’t quite up to the levels posted by its larger brother.

We measure 762.5 to 1, which is an average contrast ratio result. There are plenty of screens on both sides of that level. While the image has reasonable depth and pop, the larger Asus and Dell monitors deliver a bit more dynamic range.

Somewhere around 50 cd/m2 is a practical minimum standard for screen brightness. Any lower and you risk eyestrain and fatigue. Some monitors, such as Dell's UP2414Q, measure under that level. We recorded a minimum white level of 38.9765 cd/m2 with the backlight turned all the way down. That's a bit too dim for practical use. Raising the brightness to six gets you 50 cd/m2.

The minimum black level, however, is pretty good.

When the black level is this low, you can’t tell that the monitor is even turned on; only our i1Pro knows the truth. If you turn up the backlight to six, the black level is a still-low .0652 cd/m2. Like the UP3214Q, the UP2414Q demonstrates very consistent contrast performance.

And here are the contrast values:

No matter where you set its backlight, the UP2414Q’s contrast falls between 760 and 780 to 1. That’s the kind of consistency we like to see in any monitor. Of course, more contrast is preferable. Dell's screen doesn’t score as high as many other less expensive displays. But maintaining the same dynamic range at all brightness levels is a sign of a well-engineered product. No matter what the viewing environment, you’ll always see the same picture.

After Calibration

Since we consider 200 cd/m2 to be an ideal point for peak output, we calibrate all of our test monitors to that value. In a room with some ambient light (like an office), this brightness level provides a sharp, punchy image with maximum detail and minimum eye fatigue. It's also the sweet spot for gamma and grayscale tracking, which we look at on the next page. In a dark room, many professionals prefer a 120 cd/m2 calibration. Realistically, there's little to no difference in the calibrated black level and contrast measurements, though.

Here is where the different backlight and pixel structure used in Dell's UP2414Q starts to exhibit a disadvantage. We’ve already established that this screen has lower native contrast than its big brother. Even after calibration, it doesn’t improve. And if you use the Uniformity Compensation feature, there is a hit to the black level.

Here are the final calibrated contrast numbers:

The calibrated contrast ratio is about the same as the uncalibrated one at 763.8 to 1. That puts it near the bottom in our comparison group, but right around the middle of all the displays we’ve tested in the last year. I'm additionally including a measurement showing the result of turning on Uniformity Compensation. It does improve screen uniformity by a measurable amount, though at a cost to contrast performance.

ANSI Contrast Ratio

Another important measure of contrast is ANSI. To perform this test, a checkerboard pattern of sixteen zero- and 100-percent squares is measured, giving us a more real-world result than on/off measurements because it tests a display’s ability to simultaneously maintain both low black and full white levels, factoring in screen uniformity as well. The average of the eight full-white measurements is divided by the average of the eight full-black measurements to arrive at the ANSI result.

The outcome lands close to the on/off number, at 710.4 to 1. This time, the reduction in contrast is only eight percent (compared to the 16-percent drop from the previous tests). Demonstrable consistency shows that high-quality components are used in the UP2414Q’s construction, particularly the grid polarizer. Consequently, there is minimal light leakage between the darkest and brightest areas of the image.

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