Dell UltraSharp U2711: Quality has a Price
by Jarred Walton on January 22, 2010 2:00 AM EST- Posted in
- Displays
Dell U2711 Color Quality
We'll start with a look at the color quality of the U2711, broken down into two areas: Color gamut and color accuracy (i.e. Delta E). We'll start by explaining the former. Color gamut refers to the ability for a display to represent all of the colors in a defined selection of colors. In this case, we use the Adobe RGB standard to define the base gamut, and we measure the percentage of that standard that a display is able to cover - higher being better.
Delta E is the difference between a requested color and the color that actually appears on the display, with lower being better - i.e. the displayed color doesn't have a large delta relative to what was requested. If a display has perfect color accuracy, Delta E will be 0.0; in practice, anything less than 1.0 is nearly perfect and no one will notice the difference. A Delta E of 2.0 or less is the desired result after calibration, meaning no one color measures higher than 2.0 on our standard 24 color palette. Such a result would be fit for use in any professional imaging environment. Finally, while Delta E of around 4.0 is visible to the naked eye, it's really a question of reference points; if you don't have something better nearby and you're not going to print or view content on other media, a result where all colors measure 4.0 or less is very good.
So how does the U2711 do in these areas? First let's look at the charts, and then we'll discuss what they mean. We used the Graphics and Adobe RGB setting on the U2711, with brightness set at 36% (~200nits) and contrast at the default 50%.
The U2711 scores extremely well in color gamut, and it achieves the 96% of Adobe RGB that Dell claims in their literature (not that most users would really notice the difference between any of the displays rated 90% to 105% - at least not after you eliminate the TN panels). Color accuracy on the other hand is a bit of a mixed bag. Dell ships a paper with test results showing the color calibration of each individual U2711, with the claim that the displays will have an average Delta E of less than 5.0 without any end-user calibration (when using the sRGB and Adobe RGB settings). Dell uses Minolta Color Analyzer CA210 and 32 test colors while we test with ColorEyes Display Pro and Monaco Optix XR Pro and 24 test colors, but our Monaco results confirm their claim. We're not sure why, but we continue to get better results using Optix XR Pro than with ColorEyes Display Pro.
As far as Optix is concerned, the U2711 achieves the rated Delta E of < 5.0 at just 2.24 without calibration, which is an excellent result. In fact the U2711 has no colors in the standard Gretag Macbeth 24 color palette score higher than 5.0 (and only reddish-pink scores a 5.0 measurement). The only LCD we've tested that did better is Dell's own 2408WFP (which also, interestingly enough, had an Adobe RGB color gamut of 105%). ColorEyes also gives an average Delta E of less than 5.0, but at 4.78 the score isn't nearly as remarkable, with nine color measurements well above 5.0. The uncalibrated (Monaco) results put the U2711 ahead of the HP LP3065, Dell 2707WFP, Samsung 245T, and LaCie 324 - and just about every other LCD we've tested.
Switch to the calibrated results and the U2711 doesn't impress quite as much relative to the competition. Monaco gives the U2711 an average Delta E of 1.06, which is great, but there are two results above 3.0 (the worst is reddish-pink again, this time at 4.31) compared to displays like the HP LP3065 where the highest measured Delta E is just 1.68. Dell's own 2707WFP, a three-year-old offering, also delivered a similar average Delta E but with only two colors above 2.0 (and still under 3.0). For a better LCD (i.e. not a TN panel), the results are really only slightly above average. It is possible different calibration software would achieve a better end result, but really we're talking about a "problem" that only the most demanding users are likely to ever notice.
Color Consistency
We added another test to try and measure the panel consistency across the entire surface. We measure Delta E at the center of the display, but what happens on the edges? To test this, we used the same profile generated in our best Delta E test result and measured Delta E again at the four corners. Most of the scores are similar, with a slight increase in average Delta E relative to the center measurement. The bottom-left corner is nearly identical to the center measurement, the top-left and bottom-right are a bit worse, and the top-right corner gets the overall worst result. While on the one hand we could say that the Delta E on the top-right is twice that of the center measurement, it's not a case of being "twice as bad". In fact, the color consistency is very good, and we didn't notice any "hot spots" are areas where the colors were clearly off relative to the rest of the LCD.
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jmurbank - Saturday, January 23, 2010 - link
You explain DPI completely wrong. DPI is dots per inch or pixels per inch. It is the space between pixels on the screen that basically has no relationship how graphics is realistically being shown on the display. Lower then 0.28 mm DPI for the monitor is better for computers while higher is OK for TV.The DPI for your desire OS is different than the DPI for your monitor. Each DPI relates to something else, but the DPI you have to look out for is the value in the OS and not the display since you are dealing with formatting issues. The calculation of how fonts are sized includes operating system DPI, so you should not change the DPI at all if you are sharing your work to others. It is best to set to the standard what everybody is using which is 96 dpi for Windows. Then change the operating system font size.
If your eyes are not what they used to be, it is best to use lower resolutions instead changing the operating system DPI or referring to a monitor that has high DPI which can look like you are viewing through a sunscreen screen for your window. Of course lower resolution screens will lose your workspace, but you will not have to rely on high DPI. To gain the workspace back, use multiple displays. Of course lower the resolution and viewing it on a LCD monitor will look blocky, but you will have to live with a poor mans technology until there is something better.
CSMR - Saturday, January 23, 2010 - link
This is nonsense. Comparing non-native low resolutions to a change in dpi at the OS level, sizes of objects are the same, but with the OS change most things are sharp while with the non-native change everything is unsharp. Using non-native resolutions is just incorrect use of the monitor.jmurbank - Saturday, January 23, 2010 - link
It is not about what is sharp and what is not sharp. LCD are basically a poor mans technology and you have to give up quality if you can not see what is on the screen. LCD are designed for notebooks for their portability and not for their quality. If we go back to a better technology such as CRT, everything just works the way it is. Using a non-native resolution is not an incorrect use or a waste of the monitor's capabilities if you can not see anything what you are doing. Sure you can setup a panning which will make a virtual resolution be viewed at a native resolution, but with a sacrifice of panning.I do not recommend changing the operating system DPI just to make sure you can read at ultra high resolutions because it will create problems in the future.
strikeback03 - Monday, January 25, 2010 - link
The only CRTs worth using were the extremely high-end models. The vast majority of CRTs are absolute crap and just about any LCD is better.CSMR - Friday, January 22, 2010 - link
Text isn't smaller when the dpi setting is correct. Unless you want it to be smaller (you might now find smaller text more readable).Some apps do override the dpi setting, in my experience only browsers (and image software - fair enough). There you have to set a zoom level. That will zoom images and text (default on IE, firefox). Well I'm on Anandtech on FF now and it zooms correctly, as do all sites I have ever visited.
Now yes, images that were mapped pixel-to-pixel before are now not as sharp at a higher setting. That's mitigated by most popular software now storing icons at various dpi settings, but is a problem for web images and I usually return to 100% zoom for photographic images. However you get the same problem if you use a non-native resolution, except instead of just a few things being unsharp, everything is including text. So that is the worst possible option you can take.
If you like a 96dpi icon on a 96dpi screen (say), then you should like a 120dpi icon on a 120dpi screen even better. (Assuming the icon has been rendered at 120dpi, which most have.) So the icons comment doesn't make any sense.
You seem to be thinking about display of computer content at a very low level, each element separately. But everything has to have the right proportions and the key measurement is physical distance. Dpi settings allow you to have the right scale while preserving the right proportions.
JarredWalton - Friday, January 22, 2010 - link
When I changed the DPI on my system, all the icons look fine, but the spacing is all messed up. They look the same size as before, but there's now a bunch of empty space surrounding each icon. (This is looking at my desktop.) They look like they use 100x100 pixels instead of 75x75 (give or take).Really, my experience is that just about everything tends to be designed assuming users are running 96DPI... it's getting a bit better, but that's the short summary. There are a lot of screen elements that just run 1:1 mapping and ignore your DPI setting. Windows Vista seems to have done more than Windows XP at addressing this area, and Win7 may be even better than Vista, but no one has really nailed this IMO.
kmmatney - Saturday, January 23, 2010 - link
I don't have great eyes, so I was a fan of larger pixel sized monitors. That is until I upgraded to windows 7. One of the big problems with Windows 7 is that you can't turn off cleartype, or at least its extremely difficult to get rid of it. So, large pixel monitors look like crap. As an example, I was using a HannsG 28" LCD @ 1920 x 1200. This was fine with Windows XP, but absolutely horrible with Windows 7. I had to get rid of this LCD, and get one with smaller pitch, just to comfortably use Windows 7. My eyes are bad enough, I don't need cleartype making things even fuzzier...erple2 - Monday, January 25, 2010 - link
I'm assuming that:CPL\System\Performance Information and Tools\Adjust Visual Effects [sidebar], uncheck "Smooth edges of screen fonts".
Doesn't work? (This was from one of the first results of:
http://www.google.com/search?q=remove+cleartpye+fr...">http://www.google.com/search?q=remove+cleartpye+fr...
)
erple2 - Monday, January 25, 2010 - link
Awesome - Google figured out what I meant. The real URL ishttp://www.google.com/search?q=remove+cleartype+fr...">http://www.google.com/search?q=remove+cleartype+fr...
CSMR - Friday, January 22, 2010 - link
Not sure what's up with your system. XP was pretty awful at this, but on Vista/Win 7 it's a very strange problem to have.