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 that'd 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.
BenQ specs the BL3200PT at 300 cd/m2 max output. But we could only get to 248.9853 cd/m2 with the Contrast control on 50. Increasing it clips detail and shifts the color of brighter image elements towards green. When a monitor is this large, however, anything over 200 cd/m2 still looks suitably bright.
AMVA technology promises better black levels and contrast than IPS, and this display certainly delivers. With the backlight on maximum, BenQ lays waste to the rest of the group. In fact, a .1046 cd/m2 result is better than many HDTVs.
Despite its lower white level, the BL3200PT offers max contrast that’s almost double the second-place X270OC, putting it far ahead of any IPS screen we’ve tested and almost all of the TN monitors too.
We believe 50 cd/m2 is a practical minimum standard for screen brightness. Any lower and you risk eyestrain and fatigue. The XL2720Z bottoms out right at 50.5889 cd/m2. This is a great light level for playing games or working in a totally darkened room. As you’ll see below, black levels and contrast hold up extremely well, too.
We’ve only seen a couple of other displays measure darker than the BL3200PT, and they had correspondingly lower minimum white levels. Remember that the BenQ is actually practical to use at its minimum backlight setting unlike some other screens.
The resulting contrast is only a little lower than the maximum. That's the sort of consistency we always look for and appreciate from any display. No matter your brightness preference, you’ll always see a contrast ratio of around 2200 to 1.
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. On many monitors, it’s also the sweet spot 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 have found this makes little to no difference on the calibrated black level and contrast measurements.
The black level doesn’t suffer one bit after calibration. It’s less than half of the second-place AOC G2460PQU. AMVA panel technology seems to surpass the excellent dark-image performance of TN, while offering better off-axis viewing performance. It’s a win-win in our opinion.
The calibrated contrast ratio is solidly over 2000 to 1, which is excellent. We’re still hoping to see HDTV-level contrast in computer monitors someday, and the BL3200PT takes a huge step towards that goal. While AMVA is unlikely to ever match plasma or OLED in the black-level department, it’s emerging as the best LCD tech so far (at least in this discipline).
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, yielding a somewhat more real-world metric than on/off readings because we see a display’s ability to simultaneously maintain both low black and full white levels, factoring in screen uniformity, too. 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.
We’ve seen feedback on early AMVA panels talking about poor uniformity and light bleed. Obviously, our sample does not suffer from those maladies. In fact, this is the first time we’ve seen a display’s ANSI result exceed its calibrated outcome, demonstrating excellent quality control on the parts of BenQ and AU Optronics.