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.
When a monitor is as wide as the 34UM95, off-axis performance needs to be top-notch, and it is. These are the best horizontal viewing photos we’ve ever seen. Aside from a little light reduction, the gray step pattern looks the same from a 45-degree angle as it does head-on. Meanwhile, in the vertical plane, there is a red shift along with lower brightness and a loss of detail in the darker steps. Still, I'd say this represents a step forward for IPS panels in general.
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 monitor. Then the surrounding eight points are measured. Their values get expressed as a percentage of the baseline, either above or below. This number gets 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 in this metric.
First up is black field uniformity.
In excess of 20 percent isn't the worst result we've recorded, but it is higher than almost every other monitor we've tested. The culprit is along the bottom edge, where hotspots are fairly easy to see. There are also light areas at the top edge. Obviously, that is where the backlight LEDs are located.
Here’s the white field measurement:
Fortunately, the above result doesn’t translate to the white field measurement. In fact, as brightness increases, the screen appears more and more uniform.
Even though these tests show a weak point in the 34UM95, it doesn’t diminish other areas where the display performs well. Overall image quality is still very good.
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. Then we simply subtract the lowest value from the highest to come up with a result. Smaller numbers mean a display is more uniform. Any value below three means a variation that is invisible to the naked eye.
Almost all of the monitors we measure have no visible color shift across the screen; LG's 34UM95 is no exception. In fact, only the bottom-right corner shows any significant difference in color accuracy. Even that error wasn't visible to me.