HP ZR2240w
Simon Baker, 18 October 2011


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It's been about 18 months since we saw some interesting new models from HP. They have of course been producing monitors and computers for many years, but it was back in September 2008 when they sparked our interest with the launch of their HP LP2475W monitor. This was an interesting model featuring an IPS panel and some pretty high end specs which at the time were quite unique in the 24" sector. There were hardly any IPS panels at this size available and the LP2475W became the first of a new wave of screens offering this technology to the masses. Around the same time HP released a 22" equivalent, again breaking from the market norm of TN Film panels, and offering a model based on S-PVA technology. Their LP2275W also became a bit of a trend setter and other manufacturers soon followed with IPS, MVA and PVA offerings in this kind of size range. In April 2010 they released their ZR range of monitors as well, including a new 24" offering and a new 21.5" model. The ZR24W was another IPS addition to the 24" market and was a very popular choice since it was again breaking market trends. It was not following the pattern of high gamut colour spaces which was becoming popular with manufacturers at the time, instead being a rare standard gamut IPS offering in the 24" space.

Now HP are set to release a collection of 4 new models in their ZR range of screens, again bound to attract a lot of attention. There will be models available in sizes of 20, 21.5, 24 and 27 inches. We have with us the 21.5" model first of all for testing (other reviews to follow soon) which is their ZR2240w. HP have stuck with IPS panel technology throughout the range and also combined this with the currently popular W-LED backlighting.

The ZR2240w is marketed as follows on HP's website: "The HP ZR2240w 54,6 cm (21.5”) LED Backlit IPS Monitor has a new LED backlight, HDMI input and 1920 x 1080 full HD resolution in an ultra-modern design that’s sleeker than ever to perfectly complement HP Z Workstations."

Specifications and Features

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

Monitor Specifications


21.5"WS (54.6 cm)

Colour Depth

16.7m (6-bit + AFRC)

Aspect Ratio


Colour Gamut

Standard gamut (~sRGB),
72% NTSC, 97% sRGB, 75.2% Adobe RGB


1920 x 1080

Panel Coating

Anti-glare (matte)

Pixel Pitch

0.248 mm


1x DVI-D (HDCP), 1x D-sub, 1x DisplayPort, 1x HDMI

Response Time

8ms G2G

Design colour

Matte black bezel and stand

Static Contrast Ratio



-5° / +35° Tilt, swivel, 90mm height, pivot

Dynamic Contrast Ratio


Special Features

4x USB 2.0 ports



VESA Compatible


Viewing Angles


Physical Dimensions

(WxHxD with stand)
508 x 367 x 234 mm

Panel Technology



With stand: 5.75 Kg

Backlight Technology



DVI cable, VGA cable, Power cord, USB cable, DisplayPort cable

The ZR2240w offers a decent range of connections which is great to see, even on a low cost screen like this. There are 1x DVI-D, 1x VGA (D-sub), 1x DisplayPort and 1x HDMI interfaces available. The digital connections are all HDCP certified as well and this range should cover most users needs nicely. Great to see DisplayPort and HDMI included for connection of popular external devices like games consoles and Blu-ray players.

The screen is packaged with cables for VGA, DVI and DisplayPort. It might have been nice to include an HDMI cable as well which would have been useful seeing as the screen offers an HDMI connection too. Presumably a cost saving exercise.

HP have included a 4 port USB 2.0 hub which is useful, and something which has been available on the previous models as well. There are no further features here such as ambient light sensors, integrated speakers, card readers etc.

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


Yes / No


Yes / No

Tilt adjust


Height adjust


Swivel adjust


Rotate adjust


VESA compliant


USB Ports


Card Reader

Audio connection

Ambient Light Sensor

HDCP Support

Touch Screen

Integrated Speakers

Hardware calibration

Uniformity correction

Design and Ergonomics

Above: front view of the screen

The ZR2240w comes in an all black design, with matte plastics used for the bezel and screen casing as well as for the stand and base. There is a small silver coloured HP logo in the centre of the top bezel and in the bottom left hand corner a badge saying 'HP ZR2240w'. The bezel is ~14mm thick on the left and right hand edges, and ever so slightly thicker at ~16mm at the top and bottom.

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

The design is the same as the older ZR24W model. You can see here that the stand has a fairly large footprint which helps to give it a sturdy base on the desk. The arm which then connects onto the back of the screen has a small gap at the back which can be used as a cable tidy.

The panel coating is a standard matte anti-glare (AG) coating. Some users complain about modern IPS panels having an overly aggressive coating. Personally I do not find the coating on this screen to be too bad but it can of course be subjective. The coating seems to be a little lighter than on some of the other models we've seen such as the Dell U2410 and the recently tested NEC P241W, with a slightly less grainy feel. It won't feel the same as some of the glossy or semi-glossy screens of course.

Above: back views of the screen and stand. Click for larger versions

The back of the screen is squared off and encased in black plastic as well. There is a larger round HP logo near the top. You will also notice that there is a carry handle situated at the top which can be useful when moving the screen around. The monitor arm and stand click easily into place onto the back of the screen and there is a plastic release button which makes it easy to disconnect if you need to.

Above: further rear views of the screen showing the stand, base and carry handle. Click for larger versions.

Above is a closer look at the base of the stand and the back of the screen. You will notice that on the left hand side of the screen there is a section which sticks out a little, where there are 2 USB 2.0 ports available. We will show a closer view of these in a moment.

Above: Front views showing minimum and maximum height adjustment from the stand. Click for larger versions

There is a reasonable height adjustment available which allows you to adjust the height within a range of 90mm. At the lowest setting the bottom of the screen is 62mm from the level of the desk. In fact at this lowest setting the height adjustment clicks into place and is locked. This is designed so that you can package and carry it more easily. There is a small plastic button on the back of the stand you can press to release the adjustment again. At the highest adjustment the bottom of the screen is 152mm above the height of the desk. The minimum and maximum range is shown in the photos above. The movement is smooth and easy to use.

Above: Side views showing profile and range of tilt adjustment. Click for larger versions

The tilt range of the screen is very wide as shown above, allowing you to obtain a comfortable angle depending on your working conditions. The movement is smooth and pretty easy to use thankfully. You may notice that the side profile of the screen is quite a bit thinner than the HZ24W model. This is thanks to the use of W-LED backlighting instead of a CCFL unit like on the old model.

Above: Demonstration image of the rotation function of the screen.

The screen offers a rotate function as shown above in case you want to switch between landscape and portrait modes. This might be useful on a smaller model like this and I always question its real value on larger screens. The movement of this is quite 'jumpy' and stiff to use however. The screens side to side swivel is quite smooth but again stiff to operate. The base does maintain its position on the desk when you make the movements though.

It's good to see the full range of adjustments available and the screen feels very sturdy and well balanced. Some of them are a little stiff to use but they are still there and the main adjustments of height and tilt are smooth and simple enough to operate which is good.

A summary of the screens ergonomic adjustments is shown below:




Ease of Use


-5° / +35°









Quite smooth







Good range of adjustments although some stiff to use. Sturdy design and feel.

The screen materials  are of a good quality and the design is attractive in my opinion. There is no audible buzz from the screen, even if you listen very closely. It also stays nice and cool during use.

Above: View of the base of the stand and closer view of base / cable tidy. Click for larger versions

Above: Side USB ports on the left hand edge and small pull out screen information panel. Click for larger version (left)

The left hand side features two USB 2.0 ports for quick connection of external devices. Always useful to see I think. Just behind this there is a small panel which pulls out to tell you some information about your screen such as product number, serial number, manufactured date and revision.

Above: view of logo and OSD operational buttons. Click for larger versions

The font used for the HP ZR2240w label is white and so does stand out a little on the all black stand. Being very picky, it might have been nicer if this was a silver / grey colour so it was a little more subtle. The labels for the OSD operational buttons are also in the same colour, and these are situated in the bottom right hand corner. There is quick access to input selection and auto configuration (for analogue signals) through these buttons, but you will need to access the main menu for the rest of the settings and options. There is a very small LED which glows blue during operation on the far right hand edge of the screen. In standby this glows amber.

Above: full range of interface connections shown. Click for larger version

Above: power connection and switch. Click for larger version

The back of the screen offers a decent array of video connections. There is (from left to right on the image above) DisplayPort, HDMI, DVI-D and D-sub available. The digital interfaces are HDCP certified. To the right of this there is the upstream USB connection and two downstream USB ports to supplement the ports on the left hand edge of the screen. A good range of options here I think and nothing really missing. Good job HP. The left hand side offers the power connection for a normal kettle lead. There is also an on/off switch as you can see.

OSD Menu

Above: view of logo and OSD operational buttons. Click for larger versions

The OSD menu is accessed quickly and easily using the left most control button. This brings you first of all to the main menu as shown below.

The main menu gives you access to 10 sub-sections. You can move up and down this list using the + (plus) and - (minus) buttons quite easily. Pressing 'ok' enters you into any of these sections where you can control the associated options. Some sections are very brief, like the brightness and contrast sections. Once inside, you can again highlight the relevant option and press ok to control it. This works well and is fairly intuitive.

There are more options available in other sections. The 'color' menu gives you access to the 3 preset colour temperature modes, as well as the customisable RGB mode. The image section gives you access to a few interesting features which we will look at throughout the course of this review. These include custom scaling, video overdrive and dynamic contrast ratio.

There are options to control the OSD menu itself and several options relating to power management in the associated sections.

The language section allows you to change the language of the menu and the information section gives you basic info about the screen and resolution.

Finally the source control menu allows you to manually change between the different interface connections. You can also quickly switch between these using the 'source' button (which is also the +) on the front of the bezel.

Overall I felt there was a good range of options available and the menu was easy enough to use. It might have been nice to see some more preset modes for different uses. The menu also sometimes seems a bit long-winded to exit if you have drilled into several layers.

You can access the monitors factory 'service' menu as well but be careful not to change anything without knowing what you've done or how to change it back. Use the menu at your own risk! To access the factory menu, hold the main 'menu' button down while powering the monitor on. Once on, press 'menu' again and there is an extra section available which has replaced the 'language' section. The colour of the menu font also turns green to indicate you are in this mode. Entering the service menu gives you some information about the screen including confirmation that it is using LG.Display's LM215WF3 e-IPS panel (the LM215WF3-SLC2 to be precise).



Power Consumption

In terms of power consumption the manufacturers spec states typical usage of 35W and 52W maximum. In standby the screen apparently uses <0.3W.

State and Brightness Setting

Power Usage (W)

Factory Default (90%)


Calibrated (47%)


Maximum Brightness (100%)


Minimum Brightness (0%)




We tested this ourselves and found that out of the box the screen used 29.7W of power while at its default 90% brightness setting. After calibration, where we had adjusted the brightness control to 47% (custom mode) and therefore the backlight intensity, this was reduced to 22.2W. In standby the screen uses only 0.1W of power. This was quite comparable of course to the other W-LED models we have tested when you compare calibrated and standby power consumptions. I have plotted the results of these measurements on the graph below:

Colour Accuracy, Black Depth and Contrast

The Panel and Backlighting Unit

The HP ZR2240w utilises an LG.Display LM215WF3-SLC2 e-IPS panel which is capable of producing 16.7 million colours. The panel itself actually uses a 6-bit colour depth with Advanced frame rate control (A-FRC) to produce the 16.7m colours. This is different to regular 8-bit IPS matrices, but this is a measure taken to achieve a lower price point for these modern lower-cost displays.

The ZR2240w uses White-LED (W-LED) backlighting. The colour space of this screen is approximately equal to the sRGB reference and is considered a 'standard gamut' backlight type. The screen covers 72% of the NTSC reference, 75.2% of the Adobe RGB reference and 97% of the sRGB space. While a 97% coverage of the sRGB space is decent enough and in line with most W-LED backlit screens, some higher end uses may require a wider gamut with a full 100% sRGB coverage (and beyond) for graphics and colour work. A wide gamut screen is another option for those wanting to work outside of the sRGB colour space.

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 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 settings of the screen were as follows:

Monitor OSD Option

Default Settings





RGB Channels


Preset Mode

Standard (6500k)

HP ZR2240w - Default Factory Settings


Default Settings

luminance (cd/m2)


Black Point (cd/m2)


Contrast Ratio



The out of the box performance of the ZR2240w was reasonable. The CIE diagram on the left confirms that the monitors colour gamut (black triangle) very closely matches the sRGB colour space (orange triangle). It extends a little past the sRGB space in greens in this 2D view of gamut but is a little short in reds.



Default gamma was recorded at 2.1 average, leaving it 4% out from the target of 2.2. Gamma was actually closer to the target 2.2 in the darkest and medium greys where it was recorded at 2.23 and 2.18. This deviated as low as 2.08 in other lighter shades however. White point was a little out here at 6014k which was 7% out from the target. Note that we are using a Spectrophotometer to make these measurements which is not sensitive to the W-LED backlight as some colorimeter devices can be. When using a standard gamut colorimeter with a W-LED backlit screen there can be a typical deviance of 300 - 600k in the white point measurement which is why some sources may refer to a different white point in this test incorrectly.


Luminance was recorded at a high 218 cd/m2 which is too high for comfortable use. The OSD is set at 90% brightness and this is far too much. At this high 218 cd/m2 luminance, the black depth was still a very good 0.21 cd/m2. This gave us a static contrast ratio of 1017:1 which is excellent for an IPS panel and a pleasing result.


Colour accuracy was fairly good at default factory settings with an average DeltaE (dE) of 2.2, ranging up to a maximum of 5.9. The screen felt fairly even at least to the naked eye, although as with most screens out of the box it was overly bright. Some minor OSD adjustments to the brightness can hopefully help improve the default set up for casual users who don't have access to a hardware calibration device. To be fair though this kind of out of the box set up should be fine for most casual users anyway, and they can just adjust the brightness control to suit their working environment.




Testing Colour Temperatures



The ZR2240w doesn't offer any defined preset modes for different uses and instead offers a set of 3 pre-configured colour temperature modes and a customisable mode with RGB controls. There are options in the 'color' menu for warm (5000k), standard (6500k) and cool (9300k). The standard mode is the default and is designed to be close to the 6500k target we aim for in our tests. We have already established that this is nearer to 6000k and is about 500k out from the specified colour temperature. As a reminder we are using an i1 Pro spectrophotometer device here which can accurately read the colour temperature of the W-LED backlighting.


We measured the colour temperature of the screen in each of the preset modes to establish how accurate the settings actually were. All other settings were left at factory defaults and no ICC profile was active. The results are recorded below:


Selected Preset Mode

Measured Colour Temperature


Warm (5000k)



Standard (6500k)



Cool (9300k)



Custom (RGB)




As you can see, the warmer the screen setting, the more close it is to the actual colour temperature the user experiences. At the warm 5000k setting there was only -20k deviance which was very good. As we've already established in the previous section, the standard 6500k mode was about 500k out and a bit too warm compared with the 6500k target. The cool 9300k setting was further out still at 7826k, again being too warm and -1474k out from the target. The 'custom' setting was measured at its default settings where RGB levels were all at maximum 255. This gave us a slightly cooler white point than the 'standard' mode, and was recorded at 6068k.



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.

HP ZR2240w - Calibrated Settings, Custom Mode

Monitor OSD Option

Adjusted Setting





Preset Mode

Custom (RGB)

RGB Controls

235, 218, 255


Calibrated Settings, Custom Mode

luminance (cd/m2)


Black Point (cd/m2)


Contrast Ratio



I first of all reverted to the 'custom' mode in the OSD menu which would allow me access to the individual RGB channels. During the calibration process this would allow me to make more adjustments at the hardware level which would help preserve grey tones and gradients during the profiling. This allowed me to obtain an optimum hardware starting point and setup before software level changes would be made at the graphics card level. Adjustments were made during the process to the brightness control and to the RGB channels as shown in the table above. After this I let the software carry out the LUT adjustments at a graphics card level 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.



The calibration was a success. The gamma discrepancy that we saw before (4%) had been almost completely corrected now to leave us with 1% deviance and an average gamma of 2.2. There was still some slight discrepancy with the gamma curve with the darkest and lightest greys but it was much smaller than before. White point was also corrected to 6538k, bringing it 1% out from the target. Luminance had been reduced to a more comfortable 120 cd/m2 after the adjustment of the OSD brightness control to 47%. Black depth was still very good at 0.12 cd/m2 and this gave us an impressive calibrated static contrast ratio of 1005:1. Colour accuracy was also improved nicely with dE average now only 0.4 and maximum only 1.1. LaCie would consider colour fidelity to be excellent.


Testing the screen with various colour gradients showed fairly smooth transitions with some slight gradation in darker tones being evident. There was also some slight banding in darker tones as well but this was very minimal and only really visible with gradients and not in normal use. There was also some very slight temporal noise evident, particularly in darker tones if you look very closely. This is a result of the FRC algorithm used to produce the 16.7 million colour palette. It's not something you'd notice in practice, and you do have to look very closely to see it.


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.




HP ZR2240w - Calibrated Settings, Standard mode

Monitor OSD Option

Adjusted Setting





Preset Mode

Standard (6500k)

RGB Controls



Calibrated Settings, Standard Mode

luminance (cd/m2)


Black Point (cd/m2)


Contrast Ratio



I switched to the standard mode again to see what could be achieved through profiling in this mode. The only hardware changes that would be made here would be to the brightness control, as the individual RGB channels would not be adjusted.



Again the calibration was a great success. In fact it had managed to correct the slight (1%) deviances we'd seen in the custom mode for gamma and white point which were not pretty much spot on and <0.5% out. The gamma curve was also more accurate across the range of greys which was good. Calibrated contrast ratio was an excellent 1002:1 and dE average was 0.3 / maximum 0.8 which was excellent.


Again, you can use our settings and try our calibrated ICC profile if you wish, which is 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



I've provided a comparison above of the ZR2240w against some of the other screens we have tested in a similar size range. Out of the box average dE was 2.2 which was very good really. The default colour accuracy of the ZR2240w was comparable to some of the W-LED + 23" IPS models we have tested including the Dell U2312HM (2.2), NEC EA232WMi (2.4) and Asus ML239H (2.3). It was also quite comparable to the default colour accuracy of the 24" HP ZR24W (2.5) which was a standard gamut CCFL unit.


The professional grade 23" NEC PA231W was better still at 1.6 dE average. A reasonable performance in terms of default colour accuracy from the ZR2240w and only a little behind some of the competition really. Some form of software profiling using a colorimeter would of course be beneficial to correct some of the colours.



Once calibrated the dE average was reduced to 0.4. 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. Some of the professional range models from NEC are even more accurate. Professional grade monitors like the NEC PA series and P241W also 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. For further information and tests of a high end professional grade screen with hardware LUT calibration, you may want to have a read of our NEC SpectraView Reference 271 review.




The black depth and contrast ratio of the ZR2240w were excellent for an IPS panel. Calibrated black depth was 0.12 cd/m2 which left us with a calibrated static contrast ratio of 1005:1. This was the highest we had seen in fact from an IPS panel and edged out the Dell U2412M as well which had taken that crown very recently at 947:1.


The BenQ EW2420 and Samsung F2380 with their AMVA and cPVA panels respectively offered some fantastic contrast ratios of ~3000:1 which IPS cannot compete with at the moment.


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Contrast Stability

I wanted to see how much variance there was in the screens contrast as we adjusted the monitor setting for brightness. In theory, brightness and contrast are two independent parameters, and good contrast is a requirement regardless of the brightness adjustment. Unfortunately, such is not always the case in practice. We recorded the screens luminance and black depth at various OSD brightness settings, and calculated the contrast ratio from there. Graphics card settings were left at default with no ICC profile or calibration active. Tests were made using an NEC branded and customised X-rite i1 Display 2 colorimeter. It should be noted that we used the BasICColor calibration software here to record these, and so luminance at default settings may vary a little from the LaCie Blue Eye Pro report.

OSD Brightness


Black Point (cd/m2)

Contrast Ratio
( x:1)














































Luminance Adjustment Range = 196.2 cd/m2

Black Point Adjustment Range = 0.19  cd/m2

Average Contrast Ratio = 1062:1

The luminance range of the screen was very wide with an overall adjustment range of 196.2 cd/m2. At the top end, the 100% brightness control returned us a luminance of 242.9 cd/m2 which was only just shy of the maximum specified figure for the screen of 250 cd/m2. The OSD menu brightness control allowed you to adjust this all the way down to 46.7 cd/m2 which was very good and should allow almost any user to obtain a comfortable setting, even when working in darkened environments and low lighting conditions. A setting of around 35 - 40% should return you a luminance of ~ 120 cd/m2 at default settings. Black point ranged from 0.23 to 0.04 cd/m2 which was again excellent for an IPS panel.

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. Between 90 and 100% the brightness range controlled is actually slightly steeper it seems as the line is not quite linear.

Static contrast ratio remained high across the range, with an average figure of 1062:1 which was excellent. It was a little less stable at the lower end of the brightness range below a setting of ~50%. These contrast measurements were plotted on the graph shown above.


Dynamic Contrast


The HP ZR2240w features a dynamic contrast ratio (DCR) control, which boasts a spec of 2,000,000:1 (2 million:1).

Dynamic contrast ratio involves controlling the backlight of the screen automatically, depending on the content shown on the screen. In bright images, the backlight is increased, and in darker images, it is decreased. For this test I would use the colorimeter to record the luminance and black depths at the two extremes. Max brightness would be recorded on an all white screen once the DCR has caught up. Black depth would be recorded on an all black screen.


The DCR feature is available in all of the preset colour temperature modes and is accessible through the 'image control' menu. There are options for on and off. The brightness control remains active in the OSD menu and is not greyed out as it is on some screens. However, if you change those setting manually it will change the brightness and the DCR function will be disabled immediately without warning.



Dynamic Contrast

Specified DCR Range

2 million : 1

Available in Presets

All modes


On / Off

Max luminance (cd/m2)


Min Black Point (cd/m2)


Max Dynamic Contrast Ratio


The tests that we carry out to measure dynamic contrast ratio involve an almost completely white and almost completely black screen. In real use you are very unlikely to ever see a full black or full white screen, and even our tests are an extreme case to be honest. Carrying out the tests in this way does give you a good indication of the screens dynamic contrast ratio in real life situations however.

Unlike a lot of screens we have tested recently, this DCR did seem to function a bit which was good. You can see the transitions with the naked eye easily as you switch between dark and light content. The changes are very fast however so there is no gradual change or subtle transition. This function seemed to control the luminance up to a maximum of about 218.7 cd/m2 and a minimum black point of 0.09 cd/m2. This gave us a useable dynamic contrast ratio of 2430:1 which was ok, but a long way off the specified 2 million:1 of course. We tested the screen with a completely all black screen but that didn't seem to turn the brightness level down any further as it does with some screens - where it actually turns the backlight off!

Even if we took the maximum luminance we measured in the previous section of 242.9 cd/m2, and the lowest black point of 0.04 cd/m2, this would still only give us a maximum theoretical DCR of 6073:1. The screen would never live up to its 2 million:1 spec though as you would have to be turning the backlight off to reach a lower black point than 0.04 cd/m2. In fact it would be then tending towards infinity:1 if you consider its black point is basically then 0 cd/m2 but this doesn't happen anyway. At least the feature works a bit for those who like DCR.


Viewing Angles

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

Viewing angles of the HP ZR2240w are very good, as you would expect from a screen based on an e-IPS panel. Horizontally there are very wide fields of view with a small contrast shift only really becoming noticeable from a fairly wide angle of about 45°. At more extreme angles the image goes a little darker and a slight pinkish tint is introduced. Vertically, the contrast shift was a little more pronounced but the fields of view were still good. The panel is free from any off-centre contrast shift which you see from VA matrices, and this is why IPS technology is so highly regarded in the colour enthusiast and professional space. It 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 there is a characteristics IPS white glow, but in normal working conditions this shouldn't present much problem. The above image was taken in a darkened room to demonstrate the white wide angle glow when viewing a black screen. There is no A-TW polarizer on this panel which is rarely used now in the market but was implemented on some older screens to improve the off centre black viewing. If you are viewing dark content from a close position to the screen you can sometimes see this pale glow on parts of the screen towards the sides and corners because of your proximity to the screen and your line of sight. The edges of the screen are at an angle from your line of sight which means you pick up this white glow to a smaller degree. This disappears as you move backwards away from the screen where the line of sight does not result in a wide angle view of parts of the screen and you can see the screen largely from head on. That is a little difficult to explain but hopefully makes sense. It is only really apparent on darker content.

Panel Uniformity

Measurements of the screens 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 above 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 luminance uniformity of the ZR2240w was mostly good. Around 90% of the screen showed very little deviation from the central point and was within 10% variation of the 120 cd/m2. There was a section in the top right hand corner where luminance uniformity was not as good, and luminance dropped down to around 97 cd/m2 (-24% deviance) which was a shame. Still overall a pretty good performance in this test.

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 very little leakage from the backlight unit here which was pleasing. There was some slight variance from the four corners, with the most noticeable leakage coming from the top right hand corner. This was not too severe at all and not something you'd notice in practice. A good result again from this relatively low cost display.


General and Office Applications

The ZR2240w has a nice high resolution of 1920 x 1080 which is good for side by side office work and a high resolution considering its relatively small 21.5" screen size. I don't think it's as practical as a 16:10 format screen with 1920 x 1200 resolution though as you do lose a bit vertically. The screen of course felt a bit smaller than a 23"/24" model with the same resolution, which you do notice when moving from one to the other. The aspect ratio of this screen is a pretty common trend in today's market with the move to multimedia orientated displays and widescreen formats.


With a pixel pitch of 0.248mm, the text was comfortable and of a decent size for prolonged office use. It was a little smaller than 23" 1920 x 1080 screens but still perfectly readable. If anything I personally preferred the slightly tighter pixel pitch and small font size on this model. It was not as small as the 0.233mm you get on a 27" screen with 2560 x 1440 which I think might be a little too small for some users. A good middle ground here from this screen I think. Picture quality was very good using the DVI and D-sub connections, with DVI providing a slightly sharper image.


You will want to turn down the default brightness setting for the screen as the luminance is too high out of the box. A reduction from 90% to around 35 - 40% should return a more comfortable luminance around the 120 cd/m2 mark out of the box. The screen is capable of offering low luminance settings through the backlight control as well which is good for those wanting to work in darker lighting conditions. Unlike some screens this is all controlled by the backlight and so you do not sacrifice contrast ratio, even at the lowest settings.


There are no preset modes available for 'text' or 'internet' here so you would have to make do with one of the other colour temperature modes set up to your preference. Some models are starting to use ambient light sensors and dynamic brightness control which I think can be useful for office use. There isn't one featured on this model however.


Ergonomically the screen was very good, with a decent range of tilt and height adjustments available. There's a rotate function as well in case you want to work in portrait mode. Some of these movements were stiff to operate though which is a shame, but the stand and design is very sturdy. The easy access 2x USB 2.0 ports on the left hand side are useful for connecting printers, cameras etc, but it might have been nice to have a card reader as well like on some other models like some of the Dell range for instance.

Above: photo of text at 1920 x 1080 (top) and 1680 x 1050 (bottom)

The screen is designed to run at its native resolution of 1920 x 1080 and at a 60Hz recommended refresh rate. However, if you want you are able to run the screen outside of this resolution. We tested the screen at a lower 1680 x 1050 resolution to see how the screen handles the interpolation of the resolution. At native resolution the text was very sharp as you can see from the top photograph. When you switch to a lower resolution the text is a little more blurry, but actually still very good. There was minimal overlap of the pixels and text was still very readable. It was certainly better than some other screens we have tested. Native resolution is still recommended where possible though.


Responsiveness and Gaming

Response Time Control

Before we get in to the get into the side by side screen comparisons I want to quickly talk about the overdrive control available through the screens OSD menu. It is available within the 'image control' section under the 'Video OverDrive' option as shown above. This allows you to manually control the overdrive / RTC impulse being applied to the pixels, with a setting of on and off available. Overdrive is designed to help improve pixel responsiveness and reduce motion blur and ghosting in practice by speeding up the transitions the pixels make to change from one colour to another. You may wish to read our specs section for some further information about overdrive / response time compensation.

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 'Video OverDrive' function off and then on. To be honest the results of both seemed to be very good. With the setting off there was a slightly more pronounced motion blur behind the moving car, but it was not too bad at all. When you enabled the feature you can spot that the blur is reduced and the moving image becomes sharper. Thankfully there is no obvious 'overshoot' introduced which can be caused where these overdrive impulses are too aggressive or poorly controlled. They can result in dark or pale artefacts and halos behind the moving object in severe cases, but there was no sign of anything like that here. The overdrive impulse seemed to work very well and didn't come with any nasty side-effects. For optimum performance in games and with fast moving images I would recommend 'Video OverDrive' is turned on.

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:

21.5" 8ms G2G LG.Display e-IPS (W-LED) - Video OverDrive = On

23" 8ms G2G LG.Display e-IPS (W-LED)

23" 5ms G2G LG.Display e-IPS (W-LED) - Trace Free setting 40

23" 5ms G2G LG.Display e-IPS (W-LED)

23" 14ms LG.Display e-IPS (W-LED)

The ZR2240w is rated by HP as having an 8ms G2G response time which implies the use of overdrive / response time compensation (RTC) technology, used to boost pixel transitions across grey to grey changes. We know this to be true as we have already looked at the OverDrive function available in the OSD menu. The panel being used is an LG.Display LM215WF3-SLC2. Have a read about response time in our specs section if any of this is new to you.

I have provided a comparison of the ZR2240w first of all above against 4  other screens we have tested which use IPS panel technology and W-LED backlighting, all in the 23" sector. The ZR2240w shows less motion blur in moving images than the LG IPS231P despite that screens rather bold spec of 5ms G2G. In fact we had already concluded from our review that the IPS231P performed much like the NEC EA232WMi which has a 14ms response time and does not use RTC technology. This goes to show that you can't always trust a reported spec. The ZR2240w shows a similar low level of motion blur to the 5ms G2G rated Asus ML239H which was positive certainly. The Dell U2312HM showed a similar low level of motion blur in these tests but did introduce a negative dark overshoot due to the poorly controlled RTC impulse. Thankfully there are no obvious overshoot issues on the HP model.


21.5" 8ms G2G LG.Display e-IPS (W-LED) - Video OverDrive = On

21.5" 8ms G2G LG.Display e-IPS (Overdrive ON)

21.5" 8ms G2G LG.Display e-IPS

I have provided a comparison of the ZR2240w against some other models in the 21.5" monitor range that we have tested. The ZR2240w performs very comparably to both of these other models in practice and all are rated with an 8ms G2G e-IPS panel. Very little to separate these three models, which is good since the two Dell offerings are well regarded in this area.

21.5" 8ms G2G LG.Display e-IPS (W-LED) - Video OverDrive = On

24" 5ms G2G LG.Display e-IPS (Overdrive Off - see review for why)

24" 6ms G2G LG.Display H-IPS

Above is a comparison of the ZR2240w against two other HP models we have tested, both 24" IPS models. The ZR2240w shows a very similar level of performance to the ZR24W in these tests. There is some slight improvement compared with the older LP2475W since although the motion blur is reduced a little on that model, there is the introduction of a slight dark overshoot artefact unfortunately.

21.5" 8ms G2G LG.Display e-IPS (W-LED) - Video OverDrive = On

24" 8ms G2G LG.Display e-IPS (W-LED)

24" 8ms G2G AU Optronics AMVA (W-LED)

23" 8ms G2G Samsung cPVA (Response Time setting = Fastest)

I have also provided a comparison of the ZR2240w against other competing 23" - 24" IPS models here. The ZR2240w offers probably the best performance out of these models. The Dell U2412M has a very low level of motion blur as well, but does have a noticeable dark overshoot which is a shame. Not too severe, but something the HP is thankfully free from. There is certainly a marked improvement over the fairly slow Samsung F2380 (cPVA panel), and frankly quite disappointing BenQ EW2420 (AMVA panel).

21.5" 8ms G2G LG.Display e-IPS (W-LED)

23.6" 2ms G2G CMO TN Film (120Hz)

22" 3ms G2G Samsung TN Film + 120Hz

I've also included a comparison above against two gamer-orientated screens, both featuring heavily overdriven TN Film panels, and 120Hz technology. The pixel responsiveness of both of these is ahead of the ZR2240w, and the 120Hz frequency allows for improved 120fps frame rates and the support of 3D content as well. The BenQ XL2410T does show some even more obvious RTC overshoot in the form of very dark trails behind the moving image (speech bubble and head) which is unfortunate, and a sign that the RTC impulse is too aggressive. The Samsung 2233RZ remains our champion in this test.

The responsiveness of the ZR2240w should be perfectly fine for gaming, even at quite high levels. For an IPS panel it is a very good performer and on par with some of the faster models we have tested which was pleasing. The overdrive control should be enabled for optimum performance and it was good to see that this hadn't introduced any adverse affects.

Additional Gaming Features

Aspect Ratio Control - The ZR2240w supports limited aspect ratio control options through the OSD 'image control' menu as shown above. There are options for 'fill to screen' and 'fill to aspect ratio' here at least. However, a defined 1:1 pixel mapping mode is lacking here.

Preset Modes - There are no specific preset modes available for gaming, so you will either have to use your standard mode, or perhaps use one of the other colour temperature modes. The dynamic contrast ratio is available in all of these modes and works to a small degree at least.


Input Lag

We've had some reader enquiries recently about input lag and so thought we would give a bit more information here before we discuss the results obtained for this display:

What is Input Lag?

Input lag is described as the lag between the output from a graphics card and the image which is displayed on the screen you are using. This should not be confused with pixel response time which describes the speed at which a pixel can change from one orientation to another. Pixel response times impact aspects such as motion blur and ghosting, whereas input lag is a delay between what is sent to the monitor, and what you actually see. Of course both do contribute to the overall performance and experience of the display when used for gaming.


Input Lag Measurement Techniques - The Stopwatch Program

Traditionally input lag has been widely measured by hooking up a CRT screen to the same graphics card and PC as the TFT display. By cloning the output, the user could provide a comparative test of the output of the CRT vs. the output of a TFT. A CRT would show no lag on top of the output from the graphics card which is vital for those wanting to play fast games, where reaction times are key. This is what many users are used to, having come from older CRT displays. Many high end gamers still use CRT's as well for high refresh rates and frame rates and so the move to a TFT can be worrying, especially when you start throwing in a conversation about lag of the output image.

By running the screens side by side in this way in clone mode, you can often see that the TFT lags behind the CRT. This is sometimes noticeable in practice even, but stopwatch programs have been used for many years to give a way to record and synchronise the output so that the difference could be recorded. High shutter speed photographs can then be taken to show just how much the TFT lags compared with the CRT. The level of lag really depends on the TFT display, and is controlled by many signal processing factors including, but not limited to the internal electronics and scaling chips. Some manufacturers even take measures to help reduce this, providing modes which bypass scaler chips and options which reduce the input lag. These are often reserved for gamer-orientated screens but the results are often quite noticeable.

This stopwatch method has been used for many years by many review websites and end users. It's easy to set up, doesn't cost anything and allows a reasonable comparative view of a CRT output vs. a TFT output. It can also be useful for providing a comparison between different models over time.

The method is admittedly not 100% accurate however. There are areas of inaccuracy inherent to this method. Some stopwatch programs are based on flash which can introduce issues with frame rate support, especially when viewed from an internet source and browser. The programs can introduce a degree of error if vsync is active and due to 2D native refresh rate settings of 60Hz. There's never been a defined standard for measuring input lag and so this has been used for a long time and widely accepted as a decent enough representation of what a user may experience.


More Advanced Measurement Techniques

Some websites take this whole area one step further and even use an oscilloscope and photosensor to measure the input lag of a display. This is of course an even more precise measurement and can help you show the true image lag along with the typical response times of a pixel transition. This is then used to give you both the overall experienced 'lag' of the image and the lag specifically between the electronics and the pixel change instruction (the pure signal processing time). We do not have access to such a method at this time and of course it would not come cheap.

We are investigating alternative means to measure input lag in the future for our reviews in an effort to help provide even more accurate results. We did not want to completely remove this section since I know it is useful to many readers and it would be missed. While it might have varying degrees of accuracy, I will say that this method has been used for many years by many sources and although there is likely a varying degree of error introduced in this method, it can still allow you to give a reasonable comparison between displays. Classification of the lag into low, medium and high for instance is possible and the method can help give you an idea of the relative output of a TFT compared with a CRT. It's an indication though as opposed to a precise measurement.

If you are particularly bothered about input lag then I would encourage you to compare results between sources and refer to other review sites as well where methods like this are used. In many cases the figures are actually quite comparable but by all means if you need absolute measurements refer to other sources as well to help with your decision.

Input Lag Classification

To help in this section we will also introduce a broader classification system for these results to help account for some of the remaining error in the method and classify each screen as one of the following levels:

  • Class 1) Less than 16ms / 1 frame lag - should be fine for gamers, even at high levels

  • Class 2) A lag of 16 - 32ms / One to two frames - moderate lag but should be fine for many gamers. Caution advised for serious gaming and FPS

  • Class 3) A lag of more than 32ms / more than 2 frames - Some noticeable lag in daily usage, not suitable for high end gaming


 Class 2

On to our tests then in their current form. The HP ZR2240w showed an average input lag of 25ms during this test, ranging up to 30ms maximum. This was on par with the older HP models we have tested (LP2475W and LP2275W) which both showed an average lag of 25ms. The HP ZR24W was a little faster at 10ms. Some other screens of a similar size like the Dell U2212H (15.6ms) and Dell ST2220T (16.3ms) showed a slightly lower level of lag. The lag of this screen has been categorised as CLASS 2 as detailed above. This should be fine for most moderate gaming still but for those wanting to play fast FPS it might prove an issue in some cases.


Movies and Video

 The following summarises the screens performance in video applications:

  • 21.5" screen size makes it a reasonably small option for an all-in-one multimedia screen, a quite a bit smaller than modern LCD TV's of course. A larger screen of 23" or above would be more suitable for movie viewing.

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

  • 1920 x 1080 resolution can support true 1080 HD resolution content

  • Digital interfaces DVI, HDMI and DisplayPort supports HDCP for any encrypted and protected content

  • Additional DisplayPort and HDMI interfaces are present and good to see as they are popular and very useful for external Blu-ray / DVD player connectivity.

  • Black depth and contrast ratio are excellent for an IPS panel. Detail in darker scenes and shadow detail should not be lost due to these measurements.

  • Dynamic contrast ratio is available but has very fast transitions and only works to a small degree. It should allow a DCR up to about 2430:1 however for those who like this technology.

  • No 'Movie' preset mode available at all so you would need to use one of the other defined colour temperature modes or your user calibrated custom mode.

  • Very good pixel responsiveness which should be able to handle fast moving scenes in movies without issue.

  • Wide viewing angles thanks to e-IPS panel technology meaning several people could view the screen at once comfortable and from a whole host of different angles.

  • Very good ergonomic adjustments available from the stand allowing you to obtain a comfortable position for movie viewing. Some movements are stiff so regular adjustment might be a pain.

  • No significant backlight leakage from the panel which was pleasing. Thankfully no leakage along any of the edges which has the potential to become distracting when watching movies, especially where black borders are present.

  • No integrated stereo speakers on this model

  • No picture in picture (PiP) or picture by picture (PbP) modes available on this model.



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The ZR2240W offered a very decent all round performance I felt for what is nowadays a relatively small screen size. Manufacturers might be forgiven for leaving the 20 - 22" sector fairly light of modern innovation, leaving it to be over-run by low cost TN Film panels for general home and light office use. HP have instead introduced something here which offers the feature set and performance of a much larger and higher end screen. There is a great range of interface connections including DisplayPort and HDMI together which should satisfy most users with external devices to connect. Ergonomically the stand offered a full range of adjustments, although some were a little difficult to use admittedly. The OSD menu also provides a good range of adjustments and extras to play with.

Performance wise the ZR2240w offered a very good all round performance that one might hope for from an IPS panel. Decent enough out-of-the-box setup and the usual very good performance once calibrated was combined with the best calibrated contrast ratio we have seen so far from an IPS panel. Pixel responsiveness was very good and the screen should easily be able to handle some fairly high levels of gaming if you need. Even areas like uniformity and backlight bleed were actually pretty good which was pleasing considering it's a relatively low cost display. Gosh, even dynamic contrast ratio worked to a degree which is something we don't find ourselves saying very often!

The ZR2240w retails for £240 GBP (inc VAT) on HP's website and can be found for between approximately £215 and £250 online through some retailers. This leaves it a little more expensive than some competing IPS based models like the Dell U2212HM (review coming very soon!) which is around £195 and the older U2211H model which is ~£180. These are all more expensive than the wide range of TN Film models as you might expect but they do offer a far better all round performance and a wide range of options and features. If you want something more than the run of the mill basic display in a smaller size like this, the ZR2240w is worth a consideration for sure.



Excellent black depth and contrast ratio for an IPS panel

Ergonomics and screen movements were quite stiff and could be better

Very good range of interface options and ergonomic adjustments

Some slight backlight bleed and uniformity issues, mostly from one corner (may vary)

Very good pixel responsiveness for gaming

Missing some features like preset modes and other aspect ratio control options


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