Dell 2707WFP: Looking for the Middle Ground of Large LCDs

Brightness and Contrast Ratio

For these tests more than any others, we depend on the hardware colorimeter and software to help calibrate the displays. As previously stated, we use a Monaco Optix XR (DTP-94) colorimeter and Monaco Optix XR Pro software. The software and hardware help users to get more accurate color from their displays. Before we get to the calibrated results, we took a quick look at the range of brightness and contrast without any color calibration.




The Dell 2707WFP achieves a higher than advertised brightness level, and it also gets the highest contrast ratio we've measured so far. In practice, it's basically about as bright as the Gateway FPD2485W, although the Gateway requires you to edit the actual color values in order to reach more moderate brightness levels. While maximum brightness might be good for marketing purposes, in practice we generally don't recommend going much above 300 cd/m², and often 200 cd/m² is a better choice. Looking at these numbers really doesn't tell you a whole lot about how a display really performs, of course.

Color Accuracy

The problem with calibrating a display is that it doesn't help all applications. Specifically, the video overlay used when watching DVDs or other movies completely bypasses any color profiles, so you are essentially stuck with the uncalibrated colors. It is possible to tweak things somewhat on many LCDs using the OSD, but the amount of color correction that can be done via the OSD pales in comparison to color correction tables, and LCDs like the Dell 3007WFP and HP LP3065 are unable to adjust anything but brightness outside of software. Ideally, we would like to see video drivers begin to apply color profiles to the overlay output as well, but we're not sure how much work that would require - or if it's even possible.

For uncalibrated color accuracy, we adjusted the brightness as well as the contrast and colors (where applicable) using a "calibrate by eye" chart and the OSD controls. Also remember that color accuracy can vary from panel to panel even within the same model, and the results we are reporting are only from looking at a single LCD. Rather than using the default 50% brightness, 50% contrast, and 100% RGB, we set the RGB values at 80% on the 2707WFP and then used 89% contrast and 74% brightness.

During testing, Monaco Optix XR Pro sends 24 color patches to the display with the colorimeter measuring the resulting values. The difference between what is requested and what the LCD actually shows is known as Delta E, with lower values being better. Any score less than one is basically "perfect" - the naked eye is not going to be able to tell the difference - and scores less than 2.0 are very nearly perfect.

Ideally, you would want all of the tested colors to have a Delta E of less than 1.0, but almost no one is likely to have problems with anything scoring below 2.0. From 2.0 to 4.0, most people still won't notice the slight inaccuracies in the color palette, but when comparing displays side by side differences may be apparent - multimedia professionals would prefer something better. Anything above 4.0 begins to represent a more significant deviance, and numerous scores above 6.0 will almost certainly be noticeable by just about anyone using the display. Consistency is also important, so a display that has very good scores overall but with high spikes on some colors may actually be worse than a display with a slightly higher but more consistent average Delta E.

We should also note that fluctuations of as much as one point in Delta E are possible during a short amount of time. It generally takes as much as 30 minutes for a display to warm up after it's first powered on, and all of our calibration and testing is performed after the displays have been running for at least one hour with their screensavers disabled.



Without any form of color correction, the color accuracy of all of these displays is generally mediocre. The human eye will compensate quite a bit for differences between displays, so for most people even an average Delta E of 6.0 isn't going to be terrible. The Dell 2707WFP rates a pretty mediocre 7.0 before calibration, near the bottom of the charts. With moderate amounts of tweaking (all within the OSD) we were not able to achieve a better result. However, the consistency of the 2707WFP's scores is in some ways better than some other displays, with nearly all of the results falling within the 6.0-8.0 range.

If uncalibrated color accuracy is your primary concern, clearly something like the Acer AL2216W is going to be better overall, as it generates a Delta E result of 2.88. Still, that particular display has other drawbacks, and it's unfortunate that none of the higher-quality displays are able to offer more accurate colors without hardware calibration. If you are primarily concerned with how a display will fare when viewing movies, these uncalibrated results are especially telling, and colors in movies do not look as good as we would like.