ASUS PB279Q

Responsiveness

Input lag

A sensitive camera and small utility called SMTT 2.0 was used to assess the latency of the ASUS PB279Q, by comparing with a range of monitors of known latency. Using this method we calculated 7.4ms (under ½ a frame) of input lag. This is influenced by both the pixel responsiveness of the monitor (element you ‘see’) and the signal delay of the monitor (element you ‘feel’). This indicates a very low signal delay, particularly for a high resolution monitor, which shouldn’t get in the way of the experience even for sensitive users. Within the confines of the 60Hz refresh rate, the monitor felt snappy and responsive.

Pixel responsiveness

We used the UFO Motion Test for ghosting and a highly sensitive camera to assess the pixel responsiveness of the monitor. The middle row of the test, which has a medium cyan background, was used. The UFO traversed the screen rapidly (in 1 second), with the test set to run at a speed of ‘3840 Pixels Per Sec’. The images below show the results of this test, as captured by the camera, using all of the ‘Trace Free’ (TF) pixel overdrive settings of the monitor from 0 (weakest acceleration) to 100 (strongest acceleration).

Trailing (various 'Trace Free' settings)

You can see that the TF setting generally had a significant impact on the pixel response behaviour of the monitor on the pixel transitions analysed. At ‘TF= 0’ you can see a bold primary trail and faint secondary trail. Using ‘TF= 20’ had little effect on the primary trail, although it did appear remove or significantly weaken the secondary trail. The ‘TF= 40’ setting, in contrast, had a significant effect on the primary trail. This was weakened significantly, appearing much fainter and therefore indicating a more rapid pixel transition speed. ‘TF= 60’ changed the nature of the trailing, which now took on a slightly bright (inverted) look in places. This is a sign of the overdrive being a little too aggressive, inducing mild overshoot (inverse ghosting) in this instance. This overshoot became far more pronounced at ‘TF= 80’, with an almost neon-looking trail. At ‘TF= 100’ there was a highly defined inverted primary trail and an additional bright secondary trail.

In this test it appeared that using a ‘Trace Free’ setting of ‘40’ was optimal. This was confirmed in broader testing. Although the default setting, ‘60’, provided a good performance overall, there was some inverse ghosting in places. Lowering this to ‘40’ eliminated this and didn’t have an observable negative impact on overall motion blur from the monitor. It is important to note that pixel response times vary depending on the shades involved in the transition, with some being a slower and some faster. As noted in this article, the movement of your own eyes is actually the most significant contributor to motion blur on a monitor. This means that, regardless of how fast the pixel transitions occur, there are certain restrictions to how smooth motion will appear. Most notably; refresh rate. To take both of these factors into account, we observed the visible response performance of the monitor in ‘real-world’ scenarios using a range of game and movie titles.

Responsiveness in games and movies

On Battlefield 4 there was a moderate degree of blur. This was not caused by weaknesses in pixel responsiveness, but rather linked to eye movement (as noted previously) and the 60Hz refresh rate of the monitor. There was a very small amount of additional trailing in places, particularly during certain dark-medium shade transitions during rapid movement. When turning sharply in the ATV (All-Terrain Vehicle) with dark green (shaded) foliage mixed in with lighter foliage you could see just a hint of additional trailing from some slower than optimal pixel transitions. This really was very subtle and not worth worrying about, though, and still dwarfed by the overall motion blur which occurs regardless. In this respect the monitor was more impressive than the 28” TN panel models which showed clear weaknesses in some pixel responses. Another real bonus was the lack of any observable overshoot (inverse ghosting).

On Dirt 3 there was, again, a moderate blur. You could see during the race modes when turning even fairly gently – and in the fast-paced Gymkhana mode it become somewhat dizzying. This was almost all down to eye movement and the 60Hz refresh rate, however. Across the broad range of transitions observed on this title (light, medium and dark shades moving against each other at various speeds) there were no obvious weaknesses in pixel responsiveness. As with Battlefield 4 there was a very small degree of additional trailing in places, but nothing to write home about. The lack of overshoot (inverse ghosting) was also very pleasing.

We also tested out our Blu-ray movie titles and found no weaknesses that could be attributed to the pixel responsiveness of the monitor. There was no trailing from sluggish pixel transitions nor any overshoot from overly aggressive pixel overdrive. The fluidity of the film titles we observed was limited by their frame rate, which is about 24fps – but that’s not something the monitor can change.

The ‘4K’ UHD experience

We’ve written an extensive article exploring the benefits and drawbacks of the 3840 x 2160 ‘4K’ UHD resolution. This article was based on experiences with a 28” model. Given that this model is 27”, the experience was extremely similar. We would therefore advise reading the article to get a decent idea of what to expect from the resolution in Windows, including whilst playing games and watching movies. We again found the ‘Medium – 125%’ scaling setting struck the best balance between readability and high-resolution goodness. The images below show the desktop displayed natively (‘Small – 100%’) and using the ‘Medium – 125’ setting, respectively. You can see that key elements such as buttons and icons go from being ‘absolutely minuscule’ to ‘rather small’.

As noted in the article, scaling can be hit and miss depending on the software you’re running. Not all programs scale cleanly and some don’t scale at all. Regardless of the scaling setting you choose to use in Windows, many applications have an independent zoom level control for the main content. The ‘4K’ resolution gives you a tremendous amount of useful work space. The images below highlight this fact. The first shows two websites open side by side and the second shows a PDF file open in Adobe Reader (left) beside a Microsoft Word document (right). The content is all very compact, allowing a lot of information to be displayed at once. But it remains crisp and clear.

Our experience in games and movies was, again, very similar to on the 28” model observed in the aforementioned article. The following images obviously don’t accurately represent what you’d actually see on the monitor, but we know that users like to see monitors ‘in action’ anyway. So here are some images of the monitor running a selection of games.

Despite the limitations addressed in the article, we still got a lot of enjoyment and useful productivity from the ‘4K’ UHD resolution of the ASUS. As our experience with monitors of this resolution grows, we still enjoy the ‘wow’ moments and huge expanse of useful desktop space just as much as when we first started using such technology.

Interpolation and upscaling

The UHD resolution of 3840 x 2160 resolution makes use of 8.29 million pixels, and is such requires a great deal of graphical horsepower when gaming or using other graphics-intensive applications. For that reason some users may wish to use a lower resolution, such as 1920 x 1080. Games consoles and other AV devices use 1920 x 1080 natively and that is in many cases the maximum resolution they will support, so it’s important to consider how this non-native resolution will look on the monitor. The screen uses an interpolation process to run at a non-native resolution such as 1920 x 1080 – and for this Full HD resolution, there are two methods of display. If you navigate to ‘Image’ – ‘Aspect Control’ you will see that the default option is ‘Full’. This essentially stretches the image so that all of the pixels of the display are used. The image below illustrates this, but in no way provides an indication of what the image looks like first hand.

The image appears noticeably soft, much softer in fact than running 1920 x 1080 natively on your typical 27” Full HD LCD. Text appears to have a soft fringe and games look like they are being viewed through some sort of soft-focus lens. If you’re expecting things to look like they would on a native ‘1080p’ display, think again. The same applies to other resolutions such as 2560 x 1440 – they simply lack the sharpness of running the resolution natively on a display of similar size. And this isn’t something that can really be improved by adjusting settings on the monitor such as sharpness or ‘VividPixel’.

The alternative is not really any more attractive. That is to run the monitor with 1:1 pixel mapping, found again in ‘Image’ – ‘Aspect Control’ as ‘1:1’. This forces the monitor to use a quarter of its available pixels and display the image with 1920 x 1080 pixels in the centre of the screen. The area is 13.5”, so it’s like looking at a 13.5” Full HD display with a large black area around it, as shown below.

It is unfortunate to see that interpolation is handled so poorly by the monitor. It’s not entirely surprising, as we saw similar performance from the 28” ‘4K’ models. The Dell P2415Q, on the other hand, handled non-native resolutions surprisingly well. Some relief is found when displaying lower than native resolution content on the screen, for example looking at a 1920 x 1080 Blu-ray movie using PC movie software. The monitor remains running at 3840 x 2160 whilst the GPU or movie software upscales the content. There was an insignificant loss of sharpness when compared to running such content on a native Full HD display, so things looked much as they should in that respect.

Conclusion

As we explore in this article, the ‘4K’ UHD resolution brings a lot to the table. There are also notable drawbacks, some of which include software-dependent factors which will hopefully be ironed out in time. Although weighing up the pros and cons of the resolution itself can be challenging, we can at least say that we found the resolution very useable and got a lot of enjoyment out of the monitor. It isn’t fair to say that this enjoyment was entirely down to the resolution, of course. The ASUS PB279Q proved itself to be a capable all-rounder with pleasing image quality overall.

The factory defaults offered a bright but otherwise fairly well balanced image. Adjusting the ‘Splendid’ mode did not really bring much to the table, with the exception of some of the ‘Low Blue Light’ style settings (such as ‘Reading’) which we feel have real utility. The colour channels did need a bit of rebalancing on our unit, but gamma was right where you’d expect it to be for normal PC use. Coupled with the very light matte (‘semi glossy’) screen surface >100% sRGB coverage, the image was vibrant and very nicely varied. The AHVA panel technology also ensured strong colour consistency, maintaining appropriate shade depth throughout the screen.

Contrast performance was also pleasing, with readings that were as good as you can hope to see on this sort of panel. Another factor which is common to this panel type is ‘AHVA glow’ (a form of IPS glow, essentially) which eats away at some peripheral detail. Despite this glow, the overall distinctions between ‘bright’ and ‘dark’ and subtleties between were pleasing. Despite being very light matte, the screen surface did provide a slight graininess to whites and light colours. Nothing approaching the levels seen on older IPS panels in particular, but still something our keen and perhaps overly fussy eyes noticed.

To round things off, responsiveness was also good on the PB279Q. There was surprisingly little input lag, particularly for a high resolution display where this can often be an issue. The pixel overdrive was also well implemented to provide about as little motion blur as you can hope for from a 60Hz LCD, using the appropriate ‘Trace Free’ setting. And this was done without any traces of ghastly inverse ghosting. The monitor’s performance was also complimented by the solid and smart aesthetic of the monitor. It wasn’t a case of form over function, either, with high levels of ergonomic flexibility, slender bezels and a decent selection of ports. If you’re in the market for a ‘4K’ UHD monitor and want strong overall performance without spending a fortune, this is certainly one to consider.

 

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