AOC i2353Ph - IPS for a nice, low priceby Chris Heinonen on January 30, 2012 12:40 AM EST
Uniformity and Contrast
The dE numbers for the AOC have looked good so far, but all of those are for the center of the screen, where backlighting should be the most even and the image should be at its best. To make sure the monitor will give a good overall experience, we also take a set of 9 measurements across the screen using the Gretag Macbeth color chart and see how it does.
The color uniformity across the monitor is surprisingly very good, with very little deviation across any of the colors. The grayscale doesn’t perform quite as well, with the center having an average dE below 1, but a couple other measurements hovering in the range of 2-3 dE. Even the two worst locations still maintained an average dE of 2.55 or less, and the majority of all the results were below 2.0 dE. Overall it has very uniform color across the display.
Since LCD panels are all lit by their backlight to provide color, any errors across the screen can often be traced back to a backlighting system that is uneven and causing those color shifts. As we look at the brightness level across the display when the center is set for 200 nits, we see the drop-off at the bottom of the screen. If the LCD panel itself is behaving the same no matter the location on the screen, the different amounts of light can easily cause the shifts in color that we saw in the last test. Here the locations that had the worst dE uniformity also have the worst brightness uniformity, which is likely the root of the problem.
Once we have found the issues with the brightness, we check to see how well the backlighting system handles darkness across the display. With the AOC there seems to be significant light leakage in the corners of the display, with black levels that are very, very high for the display. I’ve recently seen LED backlit models with good control of the backlight that can get down to very low black levels, but the black levels in the AOC remain high. Some of this is due to the IPS panel, which typically has higher black levels than other panel types. It also could be an area where corners had to be cut to make the aggressive price point that AOC targeted. Regardless of why, the absolute black level is not going to please people that are adamant about deep, dark blacks.