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Introduction

We get a lot of email and Twitter requests for reviews here at TFTCentral, and one of the most requested monitors recently has been the new 27" PB278Q from Asus. This new screen forms part of the Asus Professional line-up and follows in the footsteps of the decent influx of ultra-high WQHD resolution models in this sector. It offers a massive 27" screen size and 2560 x 1440 resolution along with high end specs and technology to match its rivals. The PB278Q sports a Samsung PLS panel, and its W-LED backlight unit offers a standard gamut sRGB colour space to work with. The wide range of features and connections mean this provides an interesting alternative to some of the Dell and Samsung models which are popular in this sector. The use of a PLS panel is interesting as well as this technology seems like it will be more widely adopted as an interesting alternative to the popular IPS technology. ViewSonic also used a PLS panel in their VP2770-LED which we tested recently, and Samsung have already released a few models of their own based on their new panel tech (S27A850D and S27B8970D for instance).

The Asus website states: "Envision bigger with 2560 x 1440 WQHD, packing four times the pixel density of 720p! New premium 16:9 wide-format PB278Q LED displays with PLS panel afford 178� wide viewing angles for better productivity, opening extra multitasking space to fit more windows and projects on-screen. ASUS exclusive Splendid Video Intelligence Technology, QuickFit Virtual Scale, and 100% sRGB fidelity ensure reality-defining colour and image accuracy, giving you true �what you imagine is what you create� power. HDMI, DisplayPort, and dual-link DVI support WQHD natively, accentuated by room-dominating audio via twin 3W speakers. To help you stay naturally focused, ergonomic design includes tilt, swivel, pivot, and height adjustment, plus streamlined cabling that keeps clutter off your desktop."

Update note 18 March 2016 - it's been brought to our attention that this model was changed in 2014 to feature a different panel. Asus seemingly moved away from the Samsung PLS panel featured at the time of this review in 2012, and instead now use an AU Optronics AHVA (IPS-type still) panel. The review here at Wecravegamestoo.com covers the differences nicely and how to tell which version of the screen you have.

Specifications and Features

The following table gives detailed information about the specs of the screen:

Manufacturers website link: Asus

The PB278Q offers a decent range of connectivity options. There are D-sub VGA, DVI (dual link), HDMI and DisplayPort connections available. The cables for all of these are even supplied in the box which is rare to see, but a nice touch. The digital interfaces support HDCP as well for encrypted content. These connections should provide you enough choice to connect most PC's and external devices nowadays. There are however no USB ports on this model which is a bit of a shame, and it would have been nice to have a couple of USB (perhaps even USB 3.0) ports available for connection of PC accessories. There are 2x 3W integrated speakers though, along with an audio input and headphone jack if needed. There are no other extras like card readers, ambient light sensors or human motion sensors.

Below is a summary of the features and connections of the screen:

Design and Ergonomics

Above: front views of the screen, click for larger versions

The PB278Q comes in an all black design, with matte plastics used for all parts. There is a 21mm thick bezel around the right/left hand sides and along the top. This is a little thicker along the bottom edge of the screen at 25mm. There is a silver 'Asus' logo in the middle of the bottom bezel and a DisplayPort / HDMI logo in a light grey font on the bottom left hand corner.

Above: front view showing OSD control buttons and base of stand.

The base of the stand is a rectangular black plastic measuring ~280 x 218mm. The arm at the back of the screen needs to be screwed into this base when you first set up the screen using the easy quick-screw fitting. On the bottom right hand edge of the screen are the OSD control buttons and the labels for these are on the front bezel as shown. We will look at the OSD in more detail in a moment. 

Above: front views of the screen. Click for larger versions

The screen is a fairly simple but pretty attractive design I think and looks and feels quite like some of the competing Dell models like their new U2713HM for example.

 
Above: rear views of the screen. Click for larger version (right)

The back of the screen is a pretty flat finish with matte black plastics used again. There is a large 'Asus' logo etched into the plastic near the top. You will notice that the screens stand can be unscrewed which allows for VESA 100mm mounting options. There is no cable tidy provided on the back of the arm unfortunately. On the side of the arm is written the adjustment range of the stand as shown above which we thought was quite a nice touch.

Above: side views showing full tilt adjustment range. Click for larger versions

The screen offers an excellent range of ergonomic adjustments. The tilt adjustment range of -5� to +20� is very good and movement is smooth. It's a little stiff sometimes to move, but nothing too bad and should provide a great deal of flexibility day to day.

Above: front views showing full height adjustment range. Click for larger versions.

The 120mm height adjustment is again very smooth to move, but a little stiff when moving the screen downwards. At its lowest setting the bottom edge of the screen is ~50mm above the level of the desk surface. When extended, the bottom edge is ~170mm above the desk.

Above: front view showing rotated portrait mode. Click for larger versions

There is also a full 90� rotation function which is smooth but a little stiff to use. Nice to see it included although its practical usability is maybe a little questionable with a screen this size.

Above: underside of the base of the stand including swivel moving disc. Click for larger version

The side to side swivel is built into the base of the stand. There is a rotating black disc which is in contact with the desk. As you move the screen side to side, the whole screen and base move (as opposed to the base staying stationary). It provides easy and smooth movements with a good range.

A summary of the screens ergonomic adjustments is shown below:

All in all the screen provided a very good range of ergonomic adjustments which should afford you a lot of flexibility depending on your uses. Materials and build were of a good quality and there was no audible noise from the screen. It also stayed pretty cool during use thanks to its W-LED backlight unit.

Above: interface connectivity options shown.

The back of the screen features the interface connections on the under side as shown above. There are DisplayPort, D-sub, DL-DVI and HDMI provided for video connectivity (with HDCP support). There is then an audio input and headphone socket. No USB ports are provided on this model unfortunately. Cables are provided in the box for all video connections which was great to see.

The screen features an internal power supply and so you only need a normal kettle lead (provided in the box) to power the screen.

OSD Menu

A
Above: view of OSD operational buttons. Click for larger version

The button on the far left offers you quick access to the Asus 'Splendid' preset modes, allowing you to quickly and easily switch between them. The modes are standard, sRGB, scenery, Theater and User mode. The second button gives you access to the QuickFit viewing grid options which we will look at a little later on. The third button (arrow down) gives quick access to the volume control as shown above. Once you are in any of these options with a moving bar, the up and down arrows can very quickly control the adjustment range if you hold them down for speedy setting changes.

The menu button brings up the main OSD of course which we will look at in a moment. The up arrow gives you quick access to the brightness control, while the final button on the right (before the power on/off button) gives you quick access to switch between the video input.

The main OSD menu is split into 6 sections down the left hand side. On the right hand side are the settings available in each section. The first 'Splendid' section gives you access to the preset modes for the screen as shown above. Each option can be reset here if required to their default states.

The 'Color' menu allows you to control the brightness and contrast. You can also control the preset colour temperature and gamma settings. In the User mode you can also control the saturation and hue as well as access the 'advanced settings' section which gives you access to the RGB channels.

The 'image' menu allows you to control a few advanced features. There is the 'trace free' option which allows you to control the monitors response time and overdrive level. The ASCR dynamic contrast ratio option is available in some modes as well, and the aspect ratio can be controlled when using non native resolutions.

The 'sound' menu gives you control over the volume and mute control if you're using the integrated speakers or have connected headphones to the audio out jack.

The 'input select' menu is self explanatory as above.

The final 'system setup' menu allows you to control a few features relating to the OSD itself.

Overall the menu software was quick and easy to use. The controls were reasonably intuitive although there are quite a few different buttons in play and you are often looking at the labels on the front of the bezel to check which button you are using. There was a good range of options though to change if you want.

Power Consumption

In terms of power consumption the manufacturers spec states typical power usage of <60W. In standby the screen is specified to use <0.5W, and when turned off it uses <0.5W.

We tested this ourselves and found that out of the box the screen used 43.9W of power while at its default brightness setting which was 90%. At the lowest brightness setting, power consumption was reduced to 20.8W and at maximum 100% brightness it reached 45.6W, all keeping below the 60W specified by the manufacturer. After calibration the brightness setting had been adjusted to 27% and the power consumption was measured at 27.2W. In standby the screen used 1.6W of power and when switched off it used 1.4W. We have plotted these measurements on the graph below for comparison with other screens:

Panel and Backlighting

Panel and Colour Depth

The Asus PB278Q utilises a Samsung LTM270DL02 Plane to Line Switching (PLS) panel which is capable of producing 16.7 million colours. This is achieved through the use of a native 8-bit panel. Some of the early marketing material about this screen had mentioned the PLS specification while also talking a bit about it using an IPS panel. It seems that this term is being used by some manufacturers since it is better known in the market, but in fact the screen is using a PLS panel. The Asus website material seems to have been updated now to make it clearer that PLS technology is being employed in this screen. At the end of the day, performance characteristics are pretty similar between modern IPS and PLS panels which is why the terms are sometimes interchanged. 

Panel Coating

The screen coating on the PB278Q is a normal anti-glare (AG) offering. Like other PLS based screens we have tested it is very light and so does not suffer from the dirty or grainy appearance of some competing IPS models. It's the same coating used on models like the Samsung S27A850D and ViewSonic VP2770-LED (also using the same PLS panel). It is not a full glossy solution of coarse which has a completely different feel than any AG coating. However, the PB278Q does not suffer from a lot of reflections like glossy coated screens can.
 

Backlighting and Colour Gamut

The PB278Q uses White-LED (W-LED) backlighting producing a colour space approximately equal to the sRGB reference. This means the screen is considered a 'standard gamut' backlight type. The gamut actually extends a little beyond the sRGB reference and the panel spec sheet states that it can cover 81% NTSC, 78.1% Adobe RGB and 99.5% of the sRGB reference spaces. For reference the sRGB space is ~72% of the NTSC space, and so with the extra coverage at 81% here, it does extend a little past that as we've seen with the other PLS screens we've tested. It looks like Asus have rounded up the 99.5% sRGB coverage to reach their "100% sRGB coverage" spec they talk about.
 

PWM Flicker Tests at Various Backlight Brightness Settings

100%                                                   50%                                                 0%

We tested the screen to establish the methods used to control backlight dimming. Our in depth article talks in more details about a common method used for this which is called Pulse Width Modulation (PWM). This technique involves the cycling of the backlight on and off when using lower brightness settings to simulate the lower luminance for the user and has been used widely for many years. A series of photos was taken using the method outlined in the article. These were taken at 100%, 50% and 0% brightness settings. These tests allow us to establish 1) whether PWM is being used to control the backlight, 2) the approximate frequency at which this operates, and 3) whether a flicker may be introduced or potentially noticeable at certain settings.

A thin white line was shown on an all-black background and a photograph was taken at a slow shutter speed of 1/8 second (in this example) as the camera was scanned left to right in front of the screen. This produces a series of white lines which can be used to identify the frequency of the PWM and how quickly the backlight is cycled on and off. The higher this frequency, the less likely you are to see artefacts and flicker. The duty cycle (the time for which the backlight is on) is also important and the shorter the duty cycle, the more potential there is that you may see flicker. Please remember that not every user would notice a flicker from the backlight but it is something to be wary of. It is also a hard thing to quantify as it is very subjective when talking about whether a user may or may not experience the side effects. We are able to at least measure the frequency of the backlight using this method and tell you whether the duty cycle is sufficiently short at certain settings that it may introduce a flicker to those sensitive to it.

The Asus PB278Q showed a cycling frequency of ~240Hz (30 lines at 1/8 second shutter speed) in the initial tests shown here. A further test at an even slower shutter speed confirmed the cycling frequency at the same ~240Hz. At 100% brightness there should be no flicker evident as the backlight is not cycled on and off using PWM. At lower settings PWM is used and the duty cycle becomes progressively shorter. Given the relatively low frequency of the PWM cycling compared with some other displays (e.g. PWM of 350Hz+) and the use of LED backlighting, there is a chance that flicker may be evident to some users as you lower the brightness setting as a result. Some screens we have tested recently (e.g. DGM IPS-27001WPH, Samsung S27B970D, ViewSonic VP2770-LED and Dell U2713HM) have not used PWM at all, but it it still a long-established technique and obviously still being used widely in the market.
 

Testing Methodology

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user.

I restored my graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using the DVI interface, and analysed using an X-rite i1 Pro Spectrophotometer (not to be confused with the new i1 Display Pro colorimeter) combined with LaCie's Blue Eye Pro software suite. An NEC branded and customised X-rite i1 Display 2 colorimeter was also used to verify the black point and contrast ratio since the i1 Pro is less reliable at the darker end.

Targets for these tests are as follows:

• CIE Diagram - validates the colour space covered by the monitors backlighting in a 2D view, with the black triangle representing the displays gamut, and other reference colour spaces shown for comparison

• Gamma - we aim for 2.2 which is the default for computer monitors

• Colour temperature / white point - we aim for 6500k which is the temperature of daylight

• Luminance - we aim for 120 cd/m², which is the recommended luminance for LCD monitors in normal lighting conditions

• Black depth - we aim for as low as possible to maximise shadow detail and to offer us the best contrast ratio

• Contrast ratio - we aim for as high as possible. Any dynamic contrast ratio controls are turned off here if present

• dE average / maximum - as low as possible. If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer. If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable. If DeltaE < 1, the color fidelity is excellent.

Default Performance and Setup

Default settings of the screen were as follows:

Asus PB278Q - Default Factory Settings, Standard Mode

    

The default set up of the screen felt ok to the naked eye really with a decent temperature and white point. However you could of course tell that, as with most screens, it was far too bright for comfortable use. The screen comes out of the box with a 90% brightness setting that will need to be turned down a fair amount certainly. In terms of measurements, the CIE diagram on the left confirms that the monitors colour gamut (black triangle) covers the sRGB colour space (orange triangle) almost completely as we expected from the panel spec sheet, which tells us there is a 99.5% sRGB coverage. It extends a little past the sRGB space in some shades, particularly in blues in this 2D view of gamut. For all intents and purposes this is a standard gamut sRGB colour space screen although there might be some slight oversaturation in some shades due to the slight over-coverage.

Default gamma was measured at 2.3 average, leaving it 5% out from the target of 2.2. This was too high in all shades really but particularly in darker greys as shown in the more detailed table above. Incidentally there is a gamma setting in the OSD menu but this only offers options for 2.2 (PC) and 1.8 (Mac) rather than giving you a wider control of the gamma from the screen itself. The white point was measured at 6761k, being only 4% out from the target of 6500k which was pretty good. You will notice that the default 'color temp' setting in the OSD is 6500k and we will test the other modes in a moment for completeness. Colour accuracy out of the box was pretty poor with an average dE of 3.4 and maximum of 10.4. Colour gradients showed smooth transitions with some slight gradation at the darker end. No banding was evident. Luminance was far too high as we had suspected, being measured at 278 cd/m² by default while at the 90% brightness setting. We achieved a very good static contrast ratio for a PLS panel of 878:1 by default as well which was pleasing.

The PB278Q is part of the Asus Professional range of monitors, but unlike some of the other models we have seen in the past it does not carry any specific factory calibration. The default setup of the screen was not great overall really and so some kind of profiling would be beneficial to get the most out of the screen. At the very least you want to turn the brightness setting down, but you don't have any simple way to correct the slight gamma and white point discrepancies, or improve the colour accuracy without a calibration tool. Maybe not an issue to your average user of course.

We also wanted to test the out of the box performance in some of the other preset modes as well. We first of all reverted to the sRGB mode:

Asus PB278Q - Default Factory Settings, sRGB mode

The sRGB mode showed a noticeable drop in luminance to the naked eye when switching to it. Oddly though the brightness setting in the OSD menu remained at 90% and so some kind of digital white level adjustment must be implemented here in this mode. We were hoping that the sRGB mode might actually provide an emulation of the slightly smaller sRGB colour space to cut back some of the small oversaturation of the monitors native gamut. However, it appears to not do this at all and the monitor remains at its full 81% NTSC native gamut. This is a bit of a shame as some users may want to closely match the sRGB colour space for their colour critical work.

Gamma remained slightly out at 2.3 average and with a 5% deviance. White point was now a little cooler at 7142k giving us a bigger 10% deviance from the target. As we had observed subjectively, the luminance was now much lower at 157 cd/m² which was more comfortable at least. However, because the digital white level had been adjusted in this mode to bring about this lower luminance, the static contrast ratio was crushed to only 500:1. Colour accuracy didn't improve either over the standard mode and dE average was still 3.4. This preset mode really only seems to allow a lower luminance setting for the screen without actually doing much else to the image of colour space. It's also at the cost of the contrast ratio so is probably not much use to most people.

We then tried the 'user' mode from the preset menu:

Asus PB278Q - Default Factory Settings, User mode

The User mode gives you further access to some other OSD controls, including the RGB channels. This mode will be useful for calibration and customisation of the image personally. The rest of the settings remained as they were in the 'standard' mode and as a result it looked the same to the naked eye. In fact our measurements showed very similar performance to the default 'standard' mode. Gamma remained slightly out at 2.3 average and with a 6% deviance. White point was 6761k, identical to the standard mode and remaining 4% out from our target. Luminance, black point and contrast ratio were pretty much exactly what we'd seen in the standard mode as well, and the colour accuracy remained as it was before with dE average of 3.5. This mode didn't offer any real change to the image out of the box compared with the standard mode but it should be useful for calibration in a moment.

Testing Colour Temperatures

The PB278Q features a range of colour temperature presets within the OSD 'color' menu as shown above. These are defined as specific temperatures with 4 different modes available. We measured the screen with the X-rite i1 Pro spectrophotometer in each of these modes to establish their colour temperature / white point in practice. All other settings were left at factory defaults and no ICC profile was active. The results are recorded below:

The colour temperature settings all seemed to be a little high (cool) compared with their desired state. The warm settings of 5000k and 5500k were ~9% out from their target. At the 6500k setting the deviance was a little smaller at only 4% which was good as this is likely to be the most widely used mode and is pretty close to our review target. The cool setting of 9300k was much cooler in reality than intended, with a 15.4% deviance at 10,731k.
 

Calibration Results

I wanted to calibrate and profile the screen to determine what was possible with optimum settings and profiling. I used the X-rite i1 Pro spectrophotometer combined with the LaCie Blue Eye Pro software package to achieve these results and reports. An NEC branded and customised X-rite i1 Display 2 was used to validate the black depth and contrast ratios due to lower end limitations of the i1 Pro device.

I reverted to the 'user' preset mode in the OSD menu which would allow me access to the individual RGB channels. Adjustments were also made during the process to the brightness control, and to the RGB channels as shown in the table above. This allowed me to obtain an optimum hardware starting point and setup before software level changes would be made at the graphics card level which would help preserve tonal values. After this I let the software carry out the LUT adjustments and create an ICC profile. The screen does not feature a hardware LUT calibration option so other than the OSD alterations, the rest of the process is carried out at a graphics card level in profiling the screen.

Average gamma had been corrected to 2.2 with 0% deviance overall according to the initial test, correcting the default 6% deviance we'd found in this preset. The 4% deviance in the white point from our target of 6500k had also been corrected here and the colour temperature was now pretty much spot on at 6513k. Luminance had also been corrected thanks to the adjustment to the brightness control, now being measured at 120 cd/m². This also gave us a calibrated black depth of 0.14 cd/m², and a very good (for a PLS panel) calibrated static contrast ratio of 858:1. Colour accuracy had also been corrected nicely, with dE average of 0.5 and maximum of 1.4. LaCie would consider colour fidelity to be excellent now overall.

Testing the screen with various colour gradients showed mostly smooth transitions. There was some slight gradation in darker tones and some banding evident due to the profile adjustments made here. Nothing too major though that would be noticeable in most normal uses. It's worth also commenting on the screen coating in this section of the review. Unlike many other competing IPS panels, this screen does not feature the usual heavy and aggressive Anti-Glare (AG) coating which can sometimes lead to grainy and dirty looking images. Instead it uses a light AG screen coating similar to that of other PLS based screens and as a result the colours look more clean and crisp, the image quality is sharp and whites in particular look more pure than they do on heavy AG coated screens. It isn't a full glossy solution which adds another level of clarity and changes the overall feel of the screen, but it is an improvement over the heavy AG coating of some alternative IPS screens.

You can use our settings and try our calibrated ICC profile if you wish, which are available in our ICC profile database. Keep in mind that results will vary from one screen to another and from one computer / graphics card to another.

Calibration Performance Comparisons

We've extended the comparisons made in this section to try and give you a better view of how each screen performs, particularly out of the box which is what is going to matter to most consumers. When comparing the default factory settings for each monitor it is important to take into account several measurement areas - gamma, white point and colour accuracy. There's no point having a low dE colour accuracy figure if the gamma curve is way off for instance. A good factory calibration requires all 3 to be well set up. We have deliberately not included luminance in this comparison since this is normally far too high by default on every screen. However, that is very easily controlled through the brightness setting (on most screens) and should not impact the other areas being measured anyway. It is easy enough to obtain a suitable luminance for your working conditions and individual preferences, but a reliable factory setup in gamma, white point and colour accuracy is important and not as easy to change accurately without a calibration tool.

From these comparisons we can also compare the calibrated colour accuracy, black depth and contrast ratio. After a calibration the gamma, white point and luminance should all be at their desired targets.

Default setup of the PB278Q was ok in some areas, but lacking in others. The gamma was a little way out (5%) from the target but not enough to cause most people a problem in day to day use. The white point was also pretty close to the target with only 4% deviance. This was a reasonably close setup to the 6500k target setting which is widely used. Subjectively the screen looked good to the naked eye and colours did not appear washed out or overly cold/warm. More accurate measurements reveal that the colour accuracy however was not very good, with dE average of 3.4 out of the box and some large discrepancies in some shades being evident. Sadly this screen does not carry any kind of specific factory calibration like some of the other Asus models, and so you will probably need a calibration device to get the most out of this screen and if you want to do any colour critical work. Once calibrated the results were very good as you would hope. You can of course try our recommended OSD settings and our calibrated ICC profile to see if they bring any improvements in image quality for you. If you need absolute accuracy then you will probably want some kind of colorimeter here.

The PB278Q had quite a similar out of the box setup to the Samsung S27A850D in fact, the first PLS based screen we tested. The high end Samsung S27B970D was more accurate out of the box as it was a professional grade (and much more expensive) screen in Samsung's range.

Default colour accuracy is compared again on the above graph, with the PB278Q having a pretty poor default colour accuracy really. It was not as bad as some other models we have tested, such as the multimedia-orientated BenQ EW2730V (6.5) or the gamer orientated-Iiyama G2773HS (8.4), but was perhaps not as good as we had hoped given it is a "professional" range monitor.

Once calibrated the dE average was reduced to 0.5. This would be classified as excellent colour fidelity by LaCie. It was not quite as low as some of the other screens here which reached down to 0.2 average, but in practice you would not notice any difference here at all. The professional range models from NEC and Eizo are even more accurate than other models shown here. Professional grade monitors like those offer other high end features which separate them from some of these other models, including extended internal processing, 3D LUT's and hardware calibration. These comparisons are based on a small selection of tests, so it should be remembered that other factors do come into play when you start talking about professional use.

The calibrated black depth and contrast ratio of the PB278Q were excellent for a PLS panel, and in fact the best we had seen from this technology so far. The calibrated static contrast ratio was 858:1, putting it ahead of the Samsung S27A850D, S27B970D and ViewSonic VP2770-LED which also use similar versions of the same Samsung PLS panel. A pleasing result from the Asus screen here, and putting it on par with some of the better IPS panels in this regard. They could not compete with the very high static contrast ratios of modern AMVA panels though which can reach up to ~3000:1 in practice.

Contrast Stability and Brightness

The luminance range of the screen was very good. At the top end the panel reached 294.43 cd/m² which was almost spot on with the specified maximum of 300 cd/m². At the lower adjustment end it could reach down to a low 57.31 cd/m² meaning the screen should be fine even in darkened room conditions for most users. It doesn't quite offer the lower adjustment range of some screens but it's still more than adequate. A brightness setting of ~26% should return you a luminance of around 120 cd/m². Black point remained low across the adjustment range, from 0.34 cd/m² down to 0.07 cd/m².

We have plotted the luminance trend on the graph above. The screen behaves as it should, with a reduction in the backlight intensity controlled by the reduction in the OSD brightness setting. This was a linear relationship overall.

Average default contrast ratio measured was ~863:1 which was excellent for a PLS panel. This seemed to fluctuate a little across the brightness adjustment range but not by anything significant.

Dynamic Contrast

We tested the DCR feature in both modes. Neither appeared to show any action of changes by the ASCR feature at all, even when switching between the extremes of white and black content. The theater mode seemed to have a relatively poor contrast ratio by default at ~675:1 and the scenery mode showed a contrast ratio only the same (857:1) as what we'd seen without the feature on in some of the other preset modes. The ASCR function was not changing the brightness of the image at all in practice.

We tested the screen with a completely 100% black screen. This resulted in the backlight being turned off after a second or so. This is how manufacturers come up with their crazy high DCR specs in the lab, including it seems Asus on this model. It should be noted that it would be extremely rare to ever see a 100% black image in real use and so this is more of a theoretical DCR than a realistic, practical DCR. So in practical terms, the DCR is useless unfortunately, not even working at all unless you happen to have a 100% black image for more than a second which is probably never going to happen. Even then, I'm not sure what point there is in turning the backlight off, only to turn it back on again when any content appears on the screen. A shameless marketing trick it seems and many manufacturers follow the same tact sadly.

Viewing Angles

Above: Viewing angles shown from front and side, and  from above and below. Click for larger image

Viewing angles of the screen are very good and very similar really to an IPS panel, and what you'd expect from a PLS technology screen. Horizontally there are very wide fields of view with a small contrast shift only really becoming noticeable from a wide angle of about 45� and beyond. Vertically, the contrast and gamma shift was a little more pronounced but the fields of view were still good. The panel is free from the off-centre contrast shift which you see from VA matrices as well which is good news, and part of the reason why IPS was always a primary choice for colour critical work. PLS is now starting to become a popular alternative thanks to its very wide viewing angles. The PLS panel is also free of the very noticeable contrast and colour tone shifts you see from TN Film panels vertically.

Above: View of an all black screen from the side. Click for larger version

On a black image, like many IPS panels, there is a white glow when viewed from an angle. This picture was taken in a darkened room though and in normal working conditions this shouldn't present much problem. There is no A-TW polarizer or equivalent film on this panel which was something rarely used in the IPS market, but was implemented on some older IPS screens to improve the off centre black viewing. Because of the size of the screen you may notice some of this glow from the corners when you are viewing it head on. This is only really noticeable in darkened room conditions and when viewing dark content and is quite similar to IPS panels.

Panel Uniformity

We wanted to test here how uniform the brightness was across the screen as well as identify any leakage from the backlight in dark lighting conditions. First of all measurements of the luminance were taken at 35 points across the panel on a pure white background. The measurements were taken using BasICColor's calibration software package, combined with the NEC customised X-rite i1 Display 2 colorimeter. The below uniformity diagram shows the difference, as a percentage, between the luminance recorded at each point on the screen, as compared with the reference point of a calibrated 120 cd/m². This is the desired level of luminance for an LCD screen in normal lighting conditions, and  the below shows the variance in the luminance across the screen compared with this point. It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.

Uniformity of Luminance

The overall uniformity of the PB278Q sample was a little variable. The upper centre section of the screen remained within a 5% deviance from the centre point but along the right and left hand edges, and also along the bottom to a less extent, the luminance dropped a bit. It ranged down to 102 cd/m² in the most extreme cases with a -17% deviance. Approximately 60% of the screen was within a 10% deviance of the 120 cd/m² central point.

Backlight Leakage

Above: All black screen in a darkened room. Click for larger version

As usual we also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. There was no severe leaking here, but the camera did pick out some clouding in the corners, mostly on the right hand side. Nothing that should be problematic in normal uses and barely visible to the naked eye.

General and Office Applications

The PB278Q features a massive 2560 x 1440 WQHD resolution which is only just a little bit less vertically than a 30" screen and becoming very widely used now in recent screens. The pixel pitch of 0.233mm and 109 Pixels Per Inch (PPI), is very small and by comparison a standard 16:10 1920 x 1200 resolution 24" model has a pixel pitch of 0.270mm and a 30" model has 0.250mm. These ultra-high res 27" models offer the tightest pixel pitch and therefore the smallest text as well. I don't find it too small personally, but day to day I am used to using resolutions of this size day to day. Some users may find the small text a little too small to read comfortably, and I'd advise caution if you are coming from a 19" or 22" screen for instance where the pixel pitch and text are much larger. I found a 27" screen to be quite a change with text size when I first used one but once you get used to it, it's hard to go back to a smaller desktop resolution. This massive resolution is equal to four times the resolution of standard 720p sets. It allows users to view greater image detail and do more with an onscreen footprint larger than that of standard displays.

The massive resolution is really good for office and general use, giving you a really big screen area to work with. It is a noticeable upgrade from a 24" 1920 x 1200 / 1920 x 1080 resolution, and it's good to see Asus have opted to go with the high res panel here rather than reverting to a 1920 x 1200 or 1920 x 1080 res panel as you may find in other lower cost 27" models. Some 1920 x 1080 27" IPS based models are starting to appear in the market now, but the added resolution of a screen like this is really beneficial. For those wanting a high resolution for CAD, design, photo work etc, this is a really good option. With its WQHD display, you enjoy 77% more desktop space than a full HD screen to spread out your windows and palettes.

The image was very sharp and crisp and text was very clear. The light AG screen coating used on the PLS panel ensured that the white backgrounds of office documents looked good, and did not suffer from the overly grainy and dirty feel of some competing IPS panels featuring heavy, aggressive AG coating. It also remained free from the reflections you might experience from a full glossy solution so seems to be a good half-way between the two. The wide viewing angles provided by PLS technology on both horizontal and vertical planes, helps minimize onscreen colour shift when viewed from different angles. The default setup of the screen was reasonable in terms of gamma and white point which should produce a decent image for office work. Colour accuracy was not very good however if you are intending to do any colour critical work, and the lack of an sRGB emulation may be a little limiting to some users given the slightly wide 81% NTSC gamut coverage. If you follow our basic OSD adjustments from our calibration process (and maybe also try our calibrated ICC profile) you should be able to get a better setup, even without a colorimeter of your own.

There was no defined 'text' or 'internet' preset mode available so you would have to set up one of the other preset modes to your liking for office work. Out of the box, the 90% default brightness is too bright for office use and measured at around 278 cd/m² in our tests. A setting of around 26% should return you a luminance close to 120 cd/m² for office use if you want, and you are able to control the brightness down to around 57 cd/m² at the 0% setting which is reasonable. Those wanting to use the screen in low lighting conditions shouldn't have much of any issue here. If you really want to be able to reduce the luminance further then the sRGB mode will restrict the luminance range more, allowing you to reach lower if you really want to. Be warned though, that is at the sacrifice of contrast ratio if you do use those modes. The screen does unfortunately use Pulse-Width modulation (PWM) to control backlight dimming and so those who suffer from eye fatigue or headaches associated with flickering backlights may want to keep this in mind. Fortunately this kind of thing doesn't affect many users overall and PWM has been used for a long time for backlight dimming.

The stand provided offers a great range of adjustments and on the most part are all easy enough to use. It's good to see a decent range of tilt, height, pivot and rotate adjustments available which should allow you to obtain a comfortable position for your office though. If you want to, you can wall or arm mount the screen as well using the VESA 100mm option. With DisplayPort and DL-DVI both supporting the full 2560 x 1440 resolution you should have a decent choice for your PC connectivity. Since the VGA input was not able to support the full resolution of the screen we did not compare the sharpness of the image between analogue and digital, but the digital picture quality was excellent. There were sadly no USB ports included on this screen, which are often handy in office environments for connection of printers, scanners, cameras etc. There are however 2x 3W integrated speakers on this model which should be ok for some casual 'office noises' and the odd mp3 or YouTube video. An audio output is provided for when you are using the HDMI or DisplayPort interfaces and audio is being sent to the screen as well over those connections in case you want to connect headphones.

Above: photo of text at 2560 x 1440 (top) and 1920 x 1080 (bottom)

The screen is designed to run at its native resolution of 2560 x 1440 and at 60Hz refresh rate. If you want to you can run it outside of this and let the image be scaled to fill the screen. At the native resolution text was very sharp and clear. We ran the screen at 1920 x 1080 which was the next step down, while still maintaining the screens 16:9 aspect ratio. Text was actually pretty good and was not blurred much. The screen is perfectly capable of being run at a lower 1920 x 1080 resolution if you wanted to, without too much degradation in the picture quality and sharpness. To give you more desktop real estate and maximum picture quality, the native resolution is of course recommended where possible.

Responsiveness and Gaming

The PB278Q is rated by Asus as having a 5ms G2G response time which implies the use of overdrive / response time compensation (RTC) technology. This is used to boost pixel transitions across grey to grey changes and improve responsiveness in practice, and reduce ghosting and blurring. The panel being used is an Samsung LTM270DL02 PLS panel.

Before we get in to the side by side screen comparisons I want to quickly talk about the 'Trace Free' control available through the screens OSD menu as shown above. It is available within the 'image' section of the menu and allows you to manually control the level of overdrive / RTC impulse being applied to the pixels. There are settings available in steps of 20, ranging from 0 - 100. You may wish to read our specs section for some further information about overdrive / response time compensation.
 

Above: side by side comparison of pixel responsiveness in all 'Trace Free' modes

The screen was tested using the chase test in PixPerAn, a good bit of software for trying to quantify differences in real terms responsiveness between monitors. As a reminder, a series of pictures are taken on the highest shutter speed and compared. The images above are the best case examples from the screen with the 'Trace Free' setting at each level. Starting with the setting at 0 there was no obvious ghosting although there was some noticeable motion blur which was quite pronounced. As you move up to setting 20 you can see with the naked eye that the blur is reduced somewhat, and the moving image becomes sharper. A setting of 40 shows another obvious improvement and most of the motion blur is now eliminated, yielding a smooth and sharp image.

Moving up again to a setting of 60 unfortunately introduced a noticeable overshoot problem, where the overdrive impulse is being too aggressively applied and results in a dark and pale trail behind the moving car. You can see this in the above image as well. This was ever so slight when at the 40 setting, but only a very small amount. From there, as you increase the Trace Free setting further above 60 the overshoot artefacts become more problematic. They become more noticeable, especially at 100 where the trail is severe. This isn't uncommon for screens with overdrive controls as normally the highest settings are too aggressive and result in these kind of overshoot problems. It did seem that a setting of 40 returned the best balance and optimum pixel responsiveness in practice, without any obvious overshoot.

Display Comparisons

The screen was tested again using the chase test in PixPerAn for the display comparisons. As a reminder, a series of pictures are taken on the highest shutter speed and compared, with the best case example shown on the left, and worst case example on the right. This should only be used as a rough guide to comparative responsiveness but is handy for a direct comparison of the impact of this setting:

27" 5ms G2G Samsung PLS (Trace Free = 40)

We have selected the 40 Trace Free overdrive setting here for the comparisons since it had returned the optimum performance. In practice the Asus PB278Q delivered low levels of motion blur and a sharp moving image in this setting. It was free of the very noticeable dark and pale overshoot artefacts caused by the overly aggressive overdrive impulse in the higher Trace Free settings.

27" 5ms G2G Samsung PLS (Trace Free = 40)

27" 12ms G2G Samsung PLS (Response Time = Advanced)

27" 5ms G2G Samsung PLS (Response Time = Faster)

27" 5ms G2G Samsung PLS (response time = faster)

We have first of all provided a comparison of the Asus PB278Q against the 3 other PLS screens we have tested so far. These are all 27" 2560 x 1440 resolution models and using similar versions of the same LTM270DL02 panel. You will see on first glance that they all offer pretty similar levels of performance in these response time tests which is probably to be expected. The Asus is perhaps ever so slightly faster than the other models though in practice. The ViewSonic VP2770-LED showed a more noticeable level of motion blur which is perhaps reflective of its more modest 12ms G2G specification. The Samsung models are very comparable to one another but there is again a slight (less than the ViewSonic) blur picked up in these tests which the Asus is free of. The Asus does however show a very small amount of overshoot and you can see a slight dark trail in the above images. It's minimal while at the 40 Trace Free setting and so seems to be a decent compromise to offer that slightly smoother and sharper image. A good performance here from the Asus and another good showing from PLS technology.

27" 5ms G2G Samsung PLS (Trace Free = 40)

27" 8ms G2G LG.Display AH-IPS

27" 12ms G2G LG.Display H-IPS

27" 6ms G2G LG.Display H-IPS

27" 6ms G2G LG.Display H-IPS

If we then compare the PB278Q against some popular 27" 2560 x 1440 resolution IPS based models we see some interesting results. In practice, the PB278Q performed very similarly to the new Dell U2713HM. They were both faster than the other 3 models shown here. The HP ZR2740w and DGM IPS-2701WPH showed higher levels of blur and the Dell U2711 showed a pretty noticeable dark overshoot issue in practice.

27" 5ms G2G Samsung PLS (Trace Free = 40)

27" 4ms G2G AU Optronics AMVA (AMA = Premium)

27" 5ms G2G LG.Display AH-IPS (overdrive = medium)

We have then provided a comparison against 2 other 27" models, this time sporting lower 1920 x 1080 resolution panels. The Asus is more responsive than both the AOC i2757Fm and BenQ GW2750HM. The BenQ uses a modern AMVA panel while the AOC uses a new IPS offering. Historically AMVA panels have been very slow, but the BenQ was one of the first of a new generation which showed a marked improvement. It has slightly more motion blur than the AOC, and also shows a slight dark overshoot which you can see in the image above, caused by a poorly controlled overdrive impulse. The Asus remains a little faster than both offerings.

27" 5ms G2G Samsung PLS (Trace Free = 40)

24" 6ms G2G AU Optronics AMVA

24" 8ms G2G LG.Display e-IPS

23" 8ms G2G LG.Display e-IPS

We have also provided a comparison of the PB278Q against 3 Dell screens which are popular in smaller sizes. We had seen some dark trailing on all three of these Dell models. While they showed low levels of blur, they did seem to suffer from a poorly controlled overdrive impulses.

27" 5ms G2G Samsung PLS (Trace Free = 40)

24" 2ms G2G AU Optronics TN Film + 120Hz (AMA = On)

27" 1ms G2G Chi Mei Innolux TN Film + 120Hz (Over Drive = 0)

22" 3ms G2G Samsung TN Film + 120Hz

We've also included a comparison above against three very fast 120Hz compatible screens we have tested. In all cases these other screens are using TN Film panels and are aimed primarily at gamers. Firstly there is a comparison against the BenQ XL2420T. This showed very low levels of motion blur, but some dark overshoot was introduced as a side-effect. The Iiyama G2773HS was very responsive and even has a quoted 1ms G2G response time. This showed very low levels of blur and had minimal issue with overshoot. The Samsung SM2233RZ performed very well in these tests and showed very low levels of motion blur also. When 120Hz mode was enabled the overdrive artefacts evident in 60Hz mode were almost completely eliminated, which is something we have seen with the BenQ XL2420T as well.

While these pixel response tests show the PB278Q to have fast transitions and low levels of motion blur, there is something else going on as well here which can't be picked out by the camera. All of these other TN Film models are running at 120Hz refresh rates, which allows for improved 120fps frame rates and the support of 3D stereoscopic content as well. This can really help improve smoothness and the overall gaming experience so these screens still have the edge when it comes to fast gaming. From a pixel response point of view this screen performed very well, but there are some other areas you still need to think about when it comes to high end gaming. It couldn't keep up with the very fast TN Film models with 120Hz support.
 

The responsiveness of the PB278Q was very good and on par with what we've come to expect from PLS panels since they first emerged. The screen provided a good control over the overdrive impulse from within the OSD menu, but a Trace Free setting of 40 seemed to return an optimum performance. The screen showed low levels of motion blur and very little overshoot in this mode. It should be more than capable of handling even fast paced games given this good response time.

Additional Gaming Features

Aspect Ratio Control - The screen offers options within the OSD 'image' menu for hardware level aspect ratio control. The options are available only when using certain non-native resolutions. Overall there are options for full, 4:3 and 1:1 pixel mapping it seems, although these aren't always all available. With some input resolutions the option is greyed out, but non-native aspect ratios are still maintained. In lower resolutions the full range of options are available. We've provided some examples of what control and results are available with different source resolutions in the table below for reference.

Preset Modes - There is no specific 'game' preset mode available from within the OSD Splendid mode menu. As such, you will probably want to set up one of the other modes to your liking for games, perhaps with a higher brightness than normal.

Input Lag

For the full reviews of the models compared here and the dates they were written (and when screens were approximately released to the market), please see our full reviews index.

Our tests here are based on the new format using SMTT 2.0. We have provided a comparison above against other models we have tested to give an indication between screens. We have only included screens which were tested using this new method to allow for a fair and realistic comparison, and have removed any models tested using the old method.

The Asus PB278Q shows a moderate level of input lag. This was measured at 16.6ms average. Note that this is the overall display lag, and so accounts for the signal processing time + an element of the pixel response time. We performed these tests at various 'Trace Free' (overdrive) settings, and settled on the tests in the fastest 100 setting as it returned the lowest average lag and should get us closest to the signal processing lag on its own. The input lag of this screen has been categorised as CLASS 2 as detailed above as it is basically 1 frame. It should be ok for a lot of gaming but perhaps not for some high end gaming or FPS. This was actually lower than we'd seen from other PLS based screens which was good news. They (bottom 3 on the graph above) had shown a lag of 26 - 29ms but the Asus had reduced this somewhat.

Movies and Video

 The following summarises the screens performance in video applications:

• 27" screen size makes it a pretty good option for an all-in-one multimedia screen and comparable to smaller LCD TV's in size.

• 16:9 aspect ratio is more well suited to videos than a 16:10 format screen, leaving smaller borders on DVD's and wide screen content.

• 2560 x 1440 resolution can support full 1080 HD (1920 x 1080) resolution content easily

• Digital interfaces support HDCP for any encrypted and protected content

• Good to see HDMI and DisplayPort provided for connection of external devices. These interfaces are widely used for games consoles and DVD / Blu-ray players.

• Light AG coating does not cause issues with reflections which glossy coatings can

• Wide brightness range adjustment possible from the display, including a good maximum luminance of ~295 cd/m² and good minimum luminance of ~57 cd/m². Should afford you very good control for different lighting conditions.

• Black depth and contrast ratio are excellent for a PLS panel and the best we have seen actually from this technology so far. Shadow detail in darker scenes should not be lost.

• Dynamic contrast ratio does not work in practice

• 'Theater' Splendid preset mode preset available which is very cool and obviously blue at default. Might be useful to set up in a different way to your main preset mode perhaps

• Very good pixel responsiveness which should be able to handle fast moving scenes in movies without issue. No real issue with overshoot as long as you stick to the Trace Free setting of 40.

• Decent range of aspect ratio control options which seem to handle popular resolutions well. Good to see 1:1 pixel mapping included as well.

• Wide viewing angles thanks to the PLS panel technology meaning several people could view the screen at once comfortable and from a whole host of different angles. On darker content the PLS white glow may present a bit of a problem if viewed from wider angles

• Good range of ergonomic adjustments available from the stand meaning it should be easy to obtain a comfortable position for multiple users or if you want to sit further away from the screen for movie viewing.

• No significantly noticeable backlight leakage, and none from the edges which is good. This type of leakage may prove an issue when watching movies where black borders are present but it is not a problem here.

• Integrated 2x 3W speakers available on this model along with an audio input connection as well. May be ok for some occasional YouTube videos etc but probably not for watching many movies. The headphone socket may also be useful to some users.

• Picture in picture (PiP) or Picture By Picture (PbP) are not available on this model.

Conclusion

The Asus PB278Q was a very good screen to use. One of it's key selling points is of course the large 27" screen size and 2560 x 1440 resolution which is certainly very nice to have for many uses. The fact that Asus have not cut back on connectivity options and stand adjustments also positions this screen as a higher end professional range offering. The inclusion of all the video cables was a nice touch here as well.

Performance wise the default setup was ok in some areas, but colour accuracy was not great. It was a shame not to see a useable sRGB emulation mode as well to cut back the slight oversaturation of the native gamut. The black depth and contrast ratio were however very pleasing and the best we've seen so far from PLS technology. The PLS panel also brought with it the great all-round performance in terms of viewing angles and responsiveness that we have come to expect. From a gaming point of view the pixel response times were very good and input lag, although not super-low, was better than we'd seen from other PLS screens before.

TAt the time of writing this review (dated at the top of the page) the PB278Q retails in the UK for ~�516 GBP (inc VAT) which puts it at a very similar cost to popular 2560 x 1440 resolution models like the Dell U2711 (�520) and Dell U2713HM (�504). It is however a bit cheaper than competing PLS models like the Samsung S27A850D (�570) and ViewSonic VP2770-LED (�600). It is of course not as low cost as some of the more basic screens out there in this sector, but then you can't expect it to be given its specs and features. Given this keen price point it's well worth a look as a higher end 27" screen I think and another pleasing showcase of what PLS panel technology can offer.