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Results: Brightness And Contrast

Dell P2714T 27-Inch Touchscreen Monitor, Reviewed
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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.

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  • 5 Hide
    killerclick , January 8, 2014 4:22 AM
    Lol touchscreens on the desktop, it was a crappy idea 2 years ago and it's a crappy idea now.
  • -2 Hide
    damianrobertjones , January 8, 2014 4:30 AM
    @killerclick: That, of course, is YOUR opinion. I'd rather have the option than not have the option. Maybe we should just stop providing options... ."Having to lift your hand from the keyboard to reach out and touch your monitor definitely takes more time."So does moving your hand from the mouse back to the keyboard. As it stands I do actually prefer having touch.
  • -6 Hide
    damianrobertjones , January 8, 2014 4:30 AM
    @killerclick: That, of course, is YOUR opinion. I'd rather have the option than not have the option. Maybe we should just stop providing options... ."Having to lift your hand from the keyboard to reach out and touch your monitor definitely takes more time."So does moving your hand from the mouse back to the keyboard. As it stands I do actually prefer having touch.
  • 1 Hide
    vaughn2k , January 8, 2014 5:05 AM
    good to have this on kiosk, than have it used by designers like me.. ;) 
  • 1 Hide
    therogerwilco , January 8, 2014 6:47 AM
    Don't talk to me about desktop monitors unless they have better resolutions than 1600p.
  • 1 Hide
    InvalidError , January 8, 2014 7:21 AM
    @damian: having options may be nice but touch-screen on the desktop for everyday computing and productivity with touch as the primary input sounds like a horrible ergonomic disaster: to use a large touch screen, you need to bring it close to your waist to avoid excessive strain on your arms but putting the display there means having to hold your head at ridiculous angles to look at the screen which is going to strain your neck.So, touch on a large screen only makes sense for occasional/intermittent use.
  • 1 Hide
    killerclick , January 8, 2014 7:47 AM
    Quote:
    @killerclick: That, of course, is YOUR opinion. I'd rather have the option than not have the option. Maybe we should just stop providing options...


    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.
  • 1 Hide
    Patrick Tobin , January 8, 2014 9:35 AM
    After having used touch extensively on desktop, laptop and tablet form factors I have to say it works really well for a desktop system for quick hits and the such and getting in and out of stuff quickly in Windows 8, on a laptop it makes very little sense though. I would rather have it than not, but not at 1920x1080.
  • 1 Hide
    hannibal , January 8, 2014 10:12 AM
    The childrens that are now using iDevices and similar can not live with traditional display if there are these in the market. In the long run non touchable monitors are gonna die out. Sooner or later there are more of those touch orientated customer than we old fossilised normal screen users... Eventually we die out and so will normal monitors. For me touch based pad with screen would be ideal for controlling win8 in my desktop. It would be on the table just like my mouse, so I don't have ro rise my hand to do something...In few years there will be a lot of 4K monitors with touch interface, because big audience have to have them...
  • -1 Hide
    Patrick Tobin , January 8, 2014 10:21 AM
    After having used touch extensively on desktop, laptop and tablet form factors I have to say it works really well for a desktop system for quick hits and the such and getting in and out of stuff quickly in Windows 8, on a laptop it makes very little sense though. I would rather have it than not, but not at 1920x1080.
  • 1 Hide
    InvalidError , January 8, 2014 10:25 AM
    Quote:
    It would be on the tabel just like my mouse, so I don't have ro rise my hand to do something...

    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.)
  • 1 Hide
    red77star , January 8, 2014 2:22 PM
    What a bunch crap they are releasing now days just to justify existence of Windows 8 which clearly is not good enough for anything. Who needs this big touch screen...nobody.
  • 1 Hide
    Stevemeister , January 8, 2014 5:03 PM
    Just what we need - kids with sticky fingers smudging up the screen
  • 2 Hide
    InvalidError , January 8, 2014 5:31 PM
    Quote:
    Just what we need - kids with sticky fingers smudging up the screen

    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.
  • 2 Hide
    rantoc , January 10, 2014 8:56 AM
    27" Touchscreen for desktops with a crappy 1080p resolution... no thx! Heck making a picture of Lego would provide smaller "pixels" =P
  • 1 Hide
    rantoc , January 10, 2014 9:01 AM
    Quote:
    The childrens that are now using iDevices and similar can not live with traditional display if there are these in the market. In the long run non touchable monitors are gonna die out. Sooner or later there are more of those touch orientated customer than we old fossilised normal screen users... Eventually we die out and so wll normal monitors.For me touch based pad with screen would be ideal for controlling win8 with my desctop. It would be on the tabel just like my mouse, so I don't have ro rise my hand to do something...In few years there will be a lot of 4K monitors with touch interface, because bid audience have to have them...
    Yeah and there will be a line to the clinic with people who have shoulder problems due to the extra stress lifting an entire arm several hrs a day rather than just a hand, i doubt the touchscreens in big format will take off without the company's making them getting sued by people who will have their life destroyed due to a poor ergonomic design!
  • 0 Hide
    radiovan , January 11, 2014 12:13 AM
    Is this the Dell "NSA edition"? WOW, this thing will be as popular as the OS it comes with.
  • 0 Hide
    game junky , January 13, 2014 6:11 AM
    Though I don't think everyone desires a touch-screen desktop monitor, I can see good applications for a touch screen - for companies using computer-based payroll platforms, a flat-panel all-in-one makes for a great kiosk. I saw one being used as a catalog browsing solution at a retailer as well and that made a lot of sense to me.Not everyone wants one, but there are places where these make sense
  • 1 Hide
    InvalidError , January 13, 2014 8:54 AM
    Quote:
    a flat-panel all-in-one makes for a great kiosk.

    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.
  • 1 Hide
    WyomingKnott , January 14, 2014 3:39 PM
    One of the most awesomely useful devices I ever saw was a pen-input version of this. It was used for teaching in a software testing class. It had the slides on it, and the instructor could annotate the slides in real-time and, if she wished, save the annotations for the next class. It was, of course, repeated on a projector.It inspired my lifelong desire (well, all my life since them) for the ultimate smartboard. Full-color e-paper, markers, erasers, and the ability to save the screen to a thumb drive and bring the same one (or a copy) up later, halfway across the country, and continue working on it. I've seen school smartboards, but the closest that I've seen to my perfect device requires a spare room next to the conference room for the rear-projector. A front projector would have peoples' shadows.
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