Response Times and Buffering

A topic that almost always comes up as a problem with LCDs is their slower response times relative to CRTs. There's no doubt that even the best LCDs still exhibit some slight pixel smearing, but the vast majority of users are okay with the level of performance we have available now. Image retention on your retinas also occurs to some extent, so even if you can completely eliminate the smearing effect at the display level you won't necessarily see a perfectly crisp transition.

Besides lag at the pixel level, there has also been discussion of late about a buffering lag that occurs within the LCD before the image is ever sent to the panel for output. This can be particularly noticeable on some HDTVs when connected to a computer, as HDTVs will often do a significant amount of image processing. Whether or not delays are caused by the internal circuitry or by the LCD crystal matrix taking a moment to align itself isn't really important; the end result is what matters, so a display that updates quicker is usually preferred, especially by gamers. We glossed over this issue in the previous reviews, but with five LCDs reviewed we can now take a closer look and see if there's any merit to claims of better response times.

The Dell 2407WFP and Gateway FPD2485W LCDs advertise 16ms TrTf and 6ms GTG response times. The older Dell 2405FPW comes with a 12ms TrTf and 16ms GTG response time, which is sort of the opposite of what we see on most current displays. The 3007WFP also lists both types of response times: 14ms TrTf and 11ms GTG. The Acer AL2216W comes with the fastest advertised response time of these displays, boasting a 5ms GTG response time, but it doesn't explicitly state a TrTf value. There are of course other LCDs that are rated even faster, and ratings aren't always accurate, so let's see how these displays compare in practical use.

We used the Dell 2407WFP as the "baseline" display, so it is on the left in all of the following images. We then started the first game demo from 3DMark03 and took numerous pictures, after which we selected the best and worst case results that we could find. With all of the LCDs running a 60 Hz refresh rate, new frames are sent to the display every 0.017 seconds, so that's our granularity. Pay attention to the value of the Time field in the following screenshots, as that will show whether the two displays are showing the same frame or not. The best-case picture is shown on the left and the worst-case is on the right; these are two samples selected out of dozens of images for each pairing of monitors.

Acer AL2216Wbd

Dell 3007WFP

Gateway FPD2485W

Dell 2405FPW

We only chose one image for the FPD2485W, and other than the difference in display brightness, the two screens appear to be virtually identical. Sorting through dozens of pictures, we couldn't find any where the 2407WFP and FPD2485W showed differing content. Those two displays, at least, are a tie when it comes to image response times - including any issues with image buffering. Of the remaining displays, only the 2405FPW is any slower than the 2407WFP, and not by much.

The Acer AL2216W ends up being the best display out of those tested when it comes to image response times - or at least the lack of buffering. The 3007WFP also appears to be slightly faster than the 2407WFP. One thing not immediately visible in the above images, however, is that while the Acer display does not appear to suffer from any image buffering, response times on certain pixel color transitions are slightly worse than the 2407WFP. There were a couple of images where we could see three instances of an object on the AL2216W versus only two images on the 2407WFP.

Having said all that, we never noticed any of this during subjective testing, and it was only when we resorted to using a camera that we could capture the slight differences between the displays. Maybe it's just that we're getting old, but our eyes don't seem to be bothered by a difference of 0.017 seconds. We strongly feel that most people won't have a problem with the slight image smearing that occurs on these LCDs, but this is something that will vary by individual. If you know you are bothered by image smearing, try out a display in person to see if it's suitable for your needs.

Color Gradients Uncalibrated Results
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  • anandtech02148 - Sunday, March 11, 2007 - link

    That viewing angle thing makes me proud of my 2yr old investment on the dell 2405fpw.
    Jarred when are they gonna give you a Dell 27inc 2707wfp to play?
    27inc seems to be the right viewing angle for my future upgrade when price drop to 700usd or so.
  • BigDDesign - Saturday, March 10, 2007 - link

    Great LCD reviews. Could you test some of the monitors that cater to graphic pros or photo pros like the Lacie 321 or NEC monitors. I currently am using a Lacie Electron Blue 22" and a Viewsonic 2050 LCDTV 20" for my workstation area. Every day I pray that my CRT will last forever. I know that someday that I'm going to have to replace my CRT with a LCD. Perfect color is top priority for some of us, over response times. With digital photography so mainstream, good color is very important to many. Perfect color is what I need.
  • kmmatney - Saturday, March 10, 2007 - link

    NewEgg has a new interesting monitor for sale, which I believe is an IPS panel, for $350. The link is here. Would be nice to review a monitor in the same price range which ay perform a lot better (with a slightly smaller screen and 4:3 aspect ratio).

    http://www.newegg.com/Product/Product.asp?Item=N82...">http://www.newegg.com/Product/Product.asp?Item=N82...
  • Bana - Saturday, March 10, 2007 - link

    I'm glad to see that you tested the input lag (buffering) of the monitors this time around. I am unfortunate enough to be able to see and feel the difference on my mom's 2405fwp (hence why I haven't bought an LCD for myself). It would have been nice to see the monitors compared to a better baseline ie: a CRT monitor to get a more repeatable measurement. It'd also be nice to see get an actual response lag range like http://www.behardware.com/articles/647-4/which-22-...">BeHardware does.

    Thanks again Anandtech. :)
  • Chadder007 - Saturday, March 10, 2007 - link

    On the color gradients....I don't understand how its supposed to look. It is supposed to look smooth throughout the colors going from dark to lighter? Or is it supposed to have a blocked look to the colors in sections?...or is that what is called banding?
  • JarredWalton - Sunday, March 11, 2007 - link

    It should be smooth, so the blocks are indeed banding. Without calibration, the banding tends to be a lot worse on some of the displays (particularly the Gateway FPD2485W).
  • Den - Saturday, March 10, 2007 - link

    What is interesting to me is that if you are not willing to spend an extra $200 on a color calibration device, the cheap Acer has FAR better colors than any of the more expensive panels that have been reviewed here so far. Indeed, since 99% plus of people don't have a calibration device, I think this should be weighed far more heavily than the calibrated values. (Obviously, professionals who do have a device will reverse this weighting, but for the rest of us...) Also, could AnandTech make their calibrated color profiles available for the rest of us to download? I realize there is some panel to panel variation so it would not be perfect for every owner of the same display, but for most I think it would be far better than the factory default.
  • JarredWalton - Saturday, March 10, 2007 - link

    I agree that the uncalibrated results are important, but at the same time I think most people will be okay with even Delta E of 6.0 if they don't know any better. Your eyes and brain are generally happy with what they see, whether or not it's 100% accurate. I've used a Dell 2405FPW for a long time without proper calibration and it never bothered me; now that I have a colorimeter, I suppose I'm seeing more "true" colors, but if I were to just walk up to a display and try to judge it it would be hard to say how it performs. For image professionals, a colorimeter should be standard equipment; for everyone else... unless the display is *really* bad, other aspects probably carry at least as much weight. The viewing angles, for example, normally don't bother us much, but the Acer panel clearly has a much narrower viewing arc.

    And since you asked, here's a link to the <a href="http://images.anandtech.com/reviews/monitor/2007/a...">http://images.anandtech.com/reviews/mon...ndtechCo... profiles</a> for all of the monitors, including both the print and standard profiles. The settings used for calibration are listed in the file names. Obviously, these are targeted at the panels we have, but as a baseline others may find them somewhat helpful. Cheers.
  • JarredWalton - Saturday, March 10, 2007 - link

    Let me try that link again. :)

    http://images.anandtech.com/reviews/monitor/2007/a...">Downloadable Color Profiles
  • anandtech02148 - Wednesday, April 4, 2007 - link

    This is very helpful Jarred, these files save us some time if we plan to invest in these monitors, it's already obnoxious to spend 600buxs on a monitor and another 1-2hr calibrating, such little details is mind boggling, and manufacture reset is not that great. Maybe they should hire a professional calibrator like yourself.

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