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 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 signal clipping.
Our comparison group consists of the last four desktop monitors reviewed at Tom’s Hardware, plus Samsung’s previous-generation S27B970D QHD screen.
This is not an exceptionally bright display, but it is bright enough for pretty much any environment we can think of (and it's slightly brighter than Samsung's previous-gen effort). There is more output available in the High Bright mode, though it comes at the expense of clipped detail and a too-cool white point.
The black level results reveal a little surprise.
The S27B971D takes a step backward from Samsung's 970 in our maximum black level measurement. While this mid-pack result isn’t bad, the 971’s black level is higher by more than double. Stick with us though; the outcome it isn’t as bad as you might think.
Here’s the final contrast result:
While the maximum contrast result is around half that of the S27B970D’s, it’s still about average for all the screens we measured in 2013. And as you’ll see, the newer Samsung has much more consistent contrast at all output levels.
We believe 50 cd/m2 is a practical minimum standard for brightness. Any lower and you risk eyestrain and fatigue. Many monitors do register under that level. The S27B971D, specifically, measures 59.8483 cd/m2 when the brightness control is bottomed. That's within a hair of the S27B970D’s result.
Samsung's previous-gen flagship returned a super-low black level of .0145 cd/m2, while the S27B971D once again runs mid-pack with a .0840 measurement. That's still pretty low, falling in line with the newer screen’s more consistent contrast performance.
We wrap up this section with the minimum contrast comparison.
And here's the consistency we’re talking about. From the top to the bottom of the S27B971D’s output range, contrast is pretty much the same no matter where you choose to set it. Since there’s no sweet spot per se, you can set the light output to more precisely match your room’s lighting conditions.
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 good for gamma and grayscale tracking, which we'll look at on the next page. In a darkened room, many professionals prefer a 120 cd/m2 calibration. We find this makes little to no difference on the calibrated black level and contrast measurements.
By now, you know what we're going to say. The calibrated black level is right where it should be to maintain a contrast ratio of just over 700:1. And it’s a tad lower than the S27B970D.
Here are the final calibrated contrast numbers.
The S27B971D’s consistent contrast performance is a vast improvement over the S27B970D’s more varied numbers. Just look at the values: 720.3, 712.2, and 718.9 to 1. That’s amazing! We measured the results at a 120 cd/m2 output level and came up with 717 to 1, with a black level of .1690 cd/m2. Although monitors with greater calibrated contrast do exist, there are none as consistent at multiple output levels.
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. The result 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.
When a display’s ANSI and on/off measurements are this close, we can reasonably draw conclusions about good engineering and the use of high-quality components. It also suggests excellent screen uniformity, which we should be able to confirm on page nine.