Results: Viewing Angles and Uniformity
The more monitors we test, the more we can see that off-axis viewing performance is dependent not only on pixel structure (IPS, PLS, TN, etc.) but the backlight technology as well. And we can see that the anti-glare layer makes a difference too.
Since we couldn’t use the AccuPel, we replaced our Windows desktop with a gray step pattern. You can see the clear advantage that IPS technology enjoys compared to the other TN-based ones we've reviewed. The view from 45 degrees to the side only shows a little light falloff and no color shift. From above (also 45 degrees), there is a tendency toward green and red, depending on the brightness level. Overall though, you won’t find off-axis image quality like this on any high-refresh TN display.
Screen Uniformity: Luminance
To measure screen uniformity, zero and 100-percent full-field patterns are used, and nine points are sampled. First, we establish a baseline measurement at the center of each screen. Then the surrounding eight points are measured. Their values get expressed as a percentage of the baseline, either above or below. This number is averaged.
It is important to remember that we only test the review sample each vendor sends us. Other examples of the same monitor can measure differently.
First up is black field uniformity.
One of the biggest complaints about entry-level IPS displays is poor black field uniformity, better known on Internet forums as light bleed. Happily, our sample does not suffer from this malady. In fact, it looks just as good as any other monitor we’ve tested, regardless of price. Measurements show slightly hotter zones across the bottom of the screen.
Here’s the white field result:
A measurement of 3.71 percent means the Tempest has near-perfect white uniformity. We couldn’t see any areas that were brighter or dimmer than the rest.
Screen Uniformity: Color
To measure color uniformity, we display an 80-percent white field and measure the Delta E error of the same nine points on the screen. Then we simply subtract the lowest value from the highest to arrive at the result. A smaller number means a display is more uniform. Any value below three means a variation that is invisible to the naked eye.
Although the X270OC finishes last in our test group, its color deviation across the screen is still invisible. To see good quality-control at such a low price gives us hope that IPS monitors will all become less expensive soon.