Uncalibrated
Before calibrating any panel, we measure zero and 100 percent signals at both ends of the brightness control range. This shows us how contrast is affected at the extremes of a monitor's luminance capability. We do not increase the contrast control past the clipping point. While doing this would increase a monitor’s light output, the brightest signal levels would not be visible, resulting in crushed highlight detail. Our numbers show the maximum light level possible with no clipping of the signal.
Our comparison group consists of the last six desktop monitors reviewed at Tom’s Hardware.

The P2714T is not an exceptionally bright monitor, but it is bright enough for any indoor environment we can think of. It wouldn't work well during an outdoor photo shoot, for example, but that's not really the role it was designed to play. The capacitive layer does exact a penalty in our measurements. Dell specifies a panel brightness of 300 cd/m2 and a monitor brightness of 270 cd/m2 in its manual. Therefore, we can say the touchscreen reduces light output by about 10 percent.
Hopefully, that results in a nice low black level.

The P2714T’s max black level is a bit on the high side compared to our test group. This is the third screen we’ve tested in the last 12 months based on a Samsung-made PLS part. The other two displays demonstrated lower black levels.
And here’s the final contrast result.

While 883.6:1 is a respectable number, it has upward potential. If the P2714T were brighter while maintaining the same black level, or if the black level could be made lower without sacrificing output, its contrast would be greatly improved
All the computer monitors we have reviewed this year lack a true black level control. The brightness slider actually changes the level of the backlight. Therefore, we can use its full range without clipping any detail at either end of the brightness scale. For our minimum luminance tests, we leave the contrast control at its default and reduce the brightness to zero.
We believe 50 cd/m2 is a practical minimum standard for screen brightness. Any lower and you risk eyestrain and fatigue. Many monitors will measure under that level. While the comparison chart shows the absolute lowest brightness for a given monitor, we also comment on the contrast and black level results at a 50 cd/m2 setting.
The P2714T has a maximum output of 41.4961 cd/m2 when brightness is set to zero.

With the backlight set to its minimum, the P2714T’s black level becomes quite good. With just over 41 cd/m2 max output, the monitor is usable, though it might be a little fatiguing. Fortunately, turning up the backlight to 50 cd/m2 only increases the black level slightly. Use a brightness setting of six to achieve this.
We’ll wrap up this section with the minimum contrast comparison.

The P2714T’s minimum contrast measurement is only a little lower than its maximum, which shows solid and consistent performance. Setting the output to 50 cd/m2 improves the contrast figure to 834.9:1 for a small gain.
After Calibration
Since we consider 200 cd/m2 to be an ideal point for peak output, we calibrate all of our test monitors to that value. In a room with some ambient light (like an office), this brightness level provides a sharp, punchy image with maximum detail and minimum eye fatigue. It's also the sweet spot for gamma and grayscale tracking, which we'll look at on the next page. In a darkened room, most professionals prefer a 120 cd/m2 calibration. We have found this makes little to no difference on the calibrated black level and contrast results.
We start with the calibrated black level. This can sometimes rise a bit from the monitor’s default state. We consider the tradeoff in contrast well worth the gain in color accuracy.

Dell's P2714T has the highest calibrated black level in our test group, but finishes just below mid-pack for all of the monitors we tested in 2013. That's decent performance.
Here are the final calibrated contrast numbers.

Contrast ratio takes a small hit when you calibrate the P2714T. Given its excellent out-of-box grayscale accuracy, we can’t strongly recommend calibrating this monitor. Your choices are a perfect white balance with decent contrast, or almost-perfect white balance with slightly more decent contrast. We’re splitting hairs here!
ANSI Contrast Ratio
Another important measure of contrast is ANSI, which we measure with a checkerboard pattern of sixteen zero and 100 percent squares. This is somewhat more real-world than on/off readings because it tests a display’s ability to simultaneously maintain both low black and full white levels, and factors in screen uniformity. The average of the eight full-white measurements is divided by the average of the eight full-black measurements to arrive at the ANSI result.

The P2714T maintains an ANSI contrast level very close to its on/off value, highlighting the solid engineering that went into Dell’s choice of a high-quality grid polarizer. Minimizing light leakage between adjacent pixels means the image is more crisp and clear to the eye.
- Dell P2714T: A 27-Inch IPS-Based Touchscreen Monitor
- Packaging, Physical Layout, And Accessories
- OSD Setup And Calibration Of The Dell P2714T
- Measurement And Calibration Methodology: How We Test
- Results: Brightness And Contrast
- Results: Grayscale Tracking And Gamma Response
- Results: Color Gamut And Performance
- Results: Viewing Angle And Uniformity
- Results: Pixel Response And Input Lag
- Touch Or Not, Dell's P2714T Is A Solid Performer
I said it's a crappy idea that's not going to catch on, and I'd prefer not to have to pay extra for it or sacrifice other aspects of the display, like resolution in this case. That said, the companies can put their R&D and marketing $ wherever they want, not my money, but it's still dumb.
So instead of injuring your arms from repetitive stress holding them up in front to touch the screen, you are going to get RSI, cramps or other problems in your neck for staring at a steeper down-angle for too many hours a day... or get both problems, albeit over a longer term than either extreme, if you put the touch-screen somewhere in-between.
This is going to be 'fun' 10-20 years down the road. (As in lawsuits due to not being warned by device manufacturers that extended use of their device in a typical setup may lead to injuries.)
On the plus side, as long as it is only the glass cover getting dirty, it is much easier to clean than a keyboard or mouse.
Kiosks is a nice use of touch since it is pretty easy to "secure" those by simply omitting unwanted access in the UI design with the rest of the system physically locked out - touch-based kiosks have been around for a long time: the first time I have seen a touch-based terminal was in a video rental store about 15 years ago and the menu was in good old 80x25 text mode.
Industrial touch applications are nice too since you can seal the display on the "dirty" hot side of the application and lock the rest on the "clean" cooled weatherproof side.
For everyday computing, touch may also have its uses such as when demonstrating stuff: instead of demonstrating software or page layouts by pointing things out on the screen with fingers and then using a keyboard/mouse to activate the object or navigate pages, clickable things can be demonstrated on-screen - you already have your fingers in there to point things out anyway.