Results: Brightness, Black Level, Contrast Ratio, And Gamma
Brightness
Brightness measurements are taken by recording the luminance output of each device displaying a full white pattern, with the brightness level set to both minimum and maximum values.
Nokia's Icon achieves the lowest maximum brightness result, though a peak of 300 nits was never an issue. The display is usable in all environments, even under direct sunlight.
In comparison, the Icon's minimum brightness score is actually pretty high. That's an artifact of Windows Phone 8's lack of a brightness slider. Instead, this is as low as we can get using the low setting.
Naturally, device comparisons are challenging with only three brightness options on the Icon. We typically dial devices into exactly 200 nits. But because the Nokia phone can't hit the number we need, we're testing at all three settings and extrapolating the results on a graph.
Black Level
Our black level measurement is the luminance output of a full black pattern after the full white has been standardized to 200 nits. It’s important to note that AMOLED displays always measure a black level of zero, since their pixels simply turn off to render black.
Boasting the only AMOLED display in our test group, the Icon is capable of a true zero black level. The iPhone distinguishes itself from the rest of the pack with a low 0.25 nit result. And the rest of the competition hovers around 0.35 nits.
Contrast Ratio
Contrast ratio is the difference between a full white pattern and a full black pattern. Due to their zero reading on black level tests, AMOLED displays are said to have an infinite contrast ratio.
The AMOLED screen wins again, as the Icon and its infinite contrast level trumps the IPS-equipped competition. Once again, the iPhone 5s' display leads the rest of the pack with an 800:1 measurement.
Gamma
Gamma compensates for the linear brightness levels displayed by a monitor, versus the nonlinear way our eyes perceive light. A gamma curve of 2.2 is what we want to see. Let's see how these devices compare:
The iPhone rules this test. While the Lumia Icon's AMOLED display is technically capable of a wider color gamut than IPS displays, these are often improperly calibrated by the operating system, resulting in disappointing results. More surprising is how poorly the Nexus 5 compares to the other IPS-equipped devices.
Color Temperature
Color temperature is a measurement in Kelvin that is used to describe how “warm” or “cool” a given display is. Ideally, as long as you're not viewing your device in direct sunlight, this should be in the 6500 range. Higher color temperatures result in a cool, bluish hue, while lower temperatures deliver a warm or reddish tone.
The Lumia Icon delivers a very cool 8300-degree color temperature. Although this result is probably higher than it should be, that's also Nokia's default setting. You do get color temperature and saturation controls, unlike most of the Icon's competition.
Color Gamut Volume
Our volume measurements are compared against both the sRGB and AdobeRGB color gamuts. A reading of 100% on sRGB and 72% on AdobeRGB is optimal for viewing the vast majority of digital content. Lower results are typically accompanied by an overly red or yellow image. Meanwhile, a higher reading is usually too blue/green.
The Icon suffers from its AMOLED display. Despite having a larger gamut of colors to choose from, we can see it's not calibrated properly. The rest of the pack displays a much more desirable result closer to the 100/72 standard.
