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HP EliteDisplay E271i Review: Solid Performance From A 27" Screen

Results: Brightness And Contrast


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. This would result in crushed highlight detail. Our numbers show the maximum light level possible with no clipping of the signal.

We chose a mix of QHD and FHD monitors from recent reviews to create our comparison charts for the E271i. It’s evident from the results that neither resolution nor price is a factor in any performance metric.

As you can see, the E271i is a fairly bright monitor. It easily beats HP’s published spec of 250 cd/m2. With this much light output, you should see a clear, crisp image, even with a good amount of sunlight coming in the window. And the screen’s anti-glare coating prevents reflections from spoiling your day.

A bright screen can sometimes mean elevated black levels, though.

The E271i is quite impressive with a low max black level of .1987 cd/m2. This speaks to the excellent engineering of the panel. Many monitors sacrifice black level in the name of brightness. HP does not have to make that concession.

This should bode well for the stock max contrast ratio.

With such a wide gap between peak white and minimum black, one naturally expects a high contrast ratio number; the E271i doesn’t disappoint. Its value of 1582.2:1 is the highest we’ve recorded this year.

For the next group of measurements, we turn down the brightness control to its minimum setting, and leave the contrast unchanged. The E271i measures 40.042 cd/m2, which is a bit below our standard of 50 cd/m2. We recommend staying above this level to avoid eyestrain. At this low brightness setting, we often see amazing black level numbers.

When we measured the E271i’s black level with the brightness control at its minimum, we had a hard time even recording a value. The i1Pro was stretched to its lower limit and many of the readings were 0 cd/m2. To arrive at the amazing value of .0042 cd/m2, we averaged 20 measurements! To put it in perspective, this is the same number we get from a ninth-generation Pioneer Elite plasma TV, which is, to this day, the undisputed king of black levels among flat panel displays.

Of course, that turns into a ridiculously high contrast number.

At over 9000:1, HP will probably hold the record in this metric for some time to come. Since it measured so high, we also calculated the contrast ratio at our minimum output standard of 50 cd/m2, just to see if it would still come out on top. At 3907.5:1, the E271i misses the top spot, held by Samsung’s S27B970D, by the tiniest of margins.

After Calibration

Since we consider 200 cd/m2 to be an ideal average 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'll look at on the next page.

We start with the calibrated black level. This can sometimes rise a bit from the monitor’s default state. We consider the tradeoff in contrast well worth the gain in color accuracy.

Though the E271i’s calibrated black level isn’t the lowest we’ve measured, it’s still quite excellent at .1969 cd/m2. If you choose to work at a white level below 200 cd/m2, you will be rewarded with even blacker blacks.

Here’s the final round-up of calibrated contrast ratio numbers.

Only the best LCD panels can maintain a calibrated contrast ratio of over 1000:1. The E271i is in the top tier for this metric. It’s also interesting to note the more expensive screens at the bottom. If maximum contrast is your ultimate goal, you don’t have to spend a lot of cash to achieve it.

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. This is somewhat more real-world than on/off measurements because it tests a display’s ability to simultaneously maintain both low black and full white levels, and factors in screen uniformity. 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.

As we pointed out in our review of the AOC Q2963PM, a high-quality grid polarizer is the most important factor in rendering a high ANSI contrast ratio. By minimizing light bleed from the brightest parts of the image, the picture appears much more crisp and well-defined.

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