AOC I2757Fh And ViewSonic VX2770Smh: Two 27" IPS Monitors

Results: Gamma And ANSI Contrast Ratio


Gamma is the measurement of luminance levels at every step in the brightness range from 0 to 100 percent. This is important because a poor gamma can either crush detail at various points, or wash it out, making the entire picture appear flat and dull. Correct gamma produces a more three-dimensional image, with greater depth and pop. Meanwhile, incorrect gamma can negatively affect image quality even in monitors with high contrast ratios.

We took gamma measurements at eleven different brightness levels from 0 to 100 percent. An average value of 2.2 is the best match for video and gaming content. Since gamma is a new metric for us, we don’t have any historical data available for comparison.

AOC performs slightly better in this measurement, staying closer to its average value of 2.2. Of the three gamma presets on the I2757Fh, the default gamma 1 setting is the best; the other two are a good deal off the mark.

Because some monitors fluctuate at different points in the brightness range, we also include the range of gamma values. A lower range number indicates superior gamma tracking.

While ViewSonic doesn’t offer any gamma controls on the VX27770Smh, the measurements are only slightly less accurate than the AOC panel.

ANSI Contrast Ratio

Another important measure of contrast is ANSI. While we haven’t previously included this benchmark, it will appear in this and all future monitor reviews. To perform this test, a checkerboard of sixteen 0 and 100 percent squares are 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.

Once again, ViewSonic maintains its lead in the contrast category.