A KM CS-200 was used to measure the luminance of white and black using a range of monitor settings, including those discussed in the calibration section. From these values, static contrast ratios were calculated. These are shown in the table below. Values for the highest white luminance, lowest black luminance and peak contrast ratio recorded highlighted in blue. Results under our ‘Test Settings’ are highlighted in black. With the exception of our ‘Test Settings’, where various adjustments were made, assume any setting not mentioned was left at default.
The UP2716D yielded an average static contrast of 792:1 with only brightness adjusted. This was reduced due to the fact that ‘Uniformity Compensation’ [UC] was set to ‘Calibrated’ [enabled]. With this disabled, as per all of the other settings we tested, the contrast was higher. In ‘Standard’ with UC disabled the contrast rose to a strong 1257:1 with the maximum value recorded using ‘Color Space = REC709’ [1263:1]. These are strong values for an IPS panel. The adjustments we made for our ‘Test Settings’ [specifically to the colour channel ‘Gain’ control] reduced the contrast to a still respectable 1053:1. The maximum white luminance recorded on this table was 289 cd/m² with the minimum a very low 21 cd/m². This provided a luminance adjustment range of 268 cd/m² with plenty of useable values. Interestingly the brightness was ‘capped’ at 189 cd/m² with UC enabled and reached this even at the default brightness of ‘75’. Increasing the brightness to ‘100’ had no effect whatsoever on either the black or white luminance. Without UC enabled the monitor responded as you’d expect as you increase brightness beyond ‘75’ – although this is not documented on the table, it was tested.
The monitor has a ‘Dynamic Contrast’ feature which can be activated in the ‘Game’ or ‘Movie’ presets. This locks off manual control of the brightness and allows the backlight to automatically adjust according to the level of ‘Light’ and ‘Dark’ on the screen. As with all current LCD monitors, the backlight is controlled as a single unit [BLU] – it therefore can’t reduce the brightness for some sections of the screen whilst increasing it for others. This implementation reacted at a moderate pace to changes in the makeup of the image, but tended towards being rather bright during mixed images with plenty of dark areas. As usual we preferred to have this feature disabled and maintain control over the backlight brightness ourselves, adjusting according to preferences and lighting as is the preferred way of doing things.
PWM [Pulse Width Modulation]
The UP2716D does not use PWM [Pulse Width Modulation] at any brightness level. Instead, DC [Direct Current] dimming is used throughout its adjustment range. The backlight is therefore considered ‘flicker-free’, which will come as welcome news to those sensitive to flickering or other side-effects of PWM usage such as PWM artifacts.
Luminance uniformity
Whilst observing a black screen in a dark room, using our test settings, we could see some backlight bleed, particularly towards the bottom left and top right corners of the screen. You can hopefully see on the image below that this was fairly minor in the grand scheme of things. Note that the photograph was taken a few metres back from the monitor to eliminate ‘IPS glow’ and that individual units can vary when it comes to backlight bleed. ‘IPS glow’ is something that is characteristic of the panel type and does not vary between units of the same model. From a normal viewing position, you can see a slightly red or silvery-blue tint towards the bottom corners of the screen in particular. The colour depends on the viewing angle, with the ‘red’ tint seeming a bit more intense than usual on this model due to the backlight used. This blooms out more noticeably if you move ‘off angle’, as shown in the viewing angles video later on in the review.
We also assessed the uniformity of lighter colours using the Spyder5ELITE to analyse 9 equally spaced quadrants running from the top left to the bottom right of the screen. The tables below shows the percentage deviation between a given quadrant and the brightest quadrant measured. The top table shows the results using our ‘Test Settings’, whereas the bottom table shows the factory defaults [including ‘Uniformity Compensation’ being set to ‘Calibrated’]. We’ve introduced the ‘Uniformity Compensation’ [UC] previously. What this does is to digitally alter brightness levels at various points of the screen to make the brightness more uniform. As we’ve explored already, this comes with a bit of a hit in contrast and maximum brightness potential. You also can’t have it enabled in certain presets or when certain adjustments are made. It’s designed to be used at the default brightness setting of ‘75’, specifically. Having said that, you should still expect it to work fairly well at lower brightness settings as well, at least when it comes to luminance uniformity. Although not documented in the table, the ‘Color Space’ settings such as ‘Adobe RGB’ offered uniformity more comparable to our ‘Test Settings’ than with UC enabled.
Under our ‘Test Settings’ the luminance uniformity of the screen was fair. The brightest point recorded was ‘quadrant 5’ in the centre of the screen [156.8 cd/m²]. The greatest deviation occurred at ‘quadrant 7’ towards the bottom left of the screen [128.9 cd/m² which is 18% dimmer than the centre]. Elsewhere deviation from the centre was 8- 14%. The luminance uniformity with UC activated was excellent. The brightest point recorded was ‘quadrant 1’ towards the top left of the screen [193.6 cd/m²]. The greatest deviation from this occurred at ‘quadrant 8’ below the centre of the screen [184.8 cd/m² which is just 5% dimmer]. Note that individual units will vary when it comes to uniformity and there can be variation beyond the measured points. The UC setting does seem to be effective, though, and Dell calibrates each individual unit in this fashion using 25 quadrants for high levels of consistency right across the screen.
Below there are contour maps to represent the deviations graphically. The top map shows the results under our ‘Test Settings’ and the bottom with the UC mode enabled [factory defaults]. Here darker greys represent lower luminance than lighter greys. The percentage deviation between each quadrant and the brightest recorded quadrant is also given.
The Spyder5ELITE was also used to analyse deviations in colour temperature [white point], using the same white quadrants analysed above. The following contour maps show deviations between each quadrant and that closest to 6500K [the D65 daylight white point target]. Deviations here are assigned DeltaE values, with higher values representing greater deviations. A Delta E